Surface-coated continuous glucose monitors

ABSTRACT

CGMs containing a sensor electrode that is partially or completely coated with one or more layers of a material containing zwitterionic polymers are disclosed. With just a single calibration after implantation, CGMs containing the zwitterionic polymer coatings show reduced discordance between detected and actual blood glucose levels, during the crucial first one to three days, where current commercially available CGMs tend to show discordance with actual blood glucose levels.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims benefit of and priority to U.S. Provisional Application No. 62/349,408 filed Jun. 13, 2016, and where permissible is hereby incorporated by reference in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

This invention was made with government support under Grants EB000244, EB000351, DE013023, CA151884 awarded by the National Institutes of Health. The government has certain rights in the invention.

FIELD OF THE INVENTION

This invention is in the field of surface-coated devices with a beneficial effect; particularly continuous glucose monitors (CGMs) in which the sensor electrode of the CGM is completely or partially coated with a zwitterionic polymer, for continuous monitoring of blood glucose levels.

BACKGROUND OF THE INVENTION

Diabetes mellitus is a metabolic disorder where blood glucose (BG) regulation is lost due to either autoimmune-mediated loss of pancreatic β-cells or eventual type 2 insulin resistance. It affects hundreds of millions of people worldwide with many still undiagnosed (Yach, et al., Nat. Med. 2006, 12, 62-66; Zimmet, et al., Nature 2001, 414, 782-787; Gabir, et al., Diabetes Care 2000, 23, 1108-1112; Zhuo, et al., Diabetes Care 2014, 37, 2557-2564). Failure to monitor and control blood glucose levels in diabetic patients can give rise to pathological disorders such as heart attack, kidney failure, nerve damage, stroke, amputation of limps, and loss of vision.

The current gold standard clinical treatment for diabetic patients is to practice Self-Monitoring of Blood Glucose (SMBG) by measuring their BG levels (BGs) from finger prick-drawn blood several times a day, and then followed by injecting insulin as necessary to bring their BGs back into a normal range (Zhuo, et al., Diabetes Care 2014, 37, 2557-2564; Clar, et al., Health Technol. Assess (Rocky) 2010, 14, 1-140; Kovatchev, et al., Methods Enzymol. 2009, 454, 69-86). However, SMBG is not capable of capturing BG fluctuation over time. These deficiencies together with the pain associated with repetitive finger prick tests render SMBG an unfavorable practice for both patients and doctors (Boland, et al. Diabetes Care 2001, 24, 1858-1862; Newman and Turner, Biosensors and Bioelectronics 2005, 20, 2435-2453).

In the last several decades more sophisticated implantable devices for glycemic tracking such as continuous glucose monitors (CGMs) have been developed (Hovorka, Diabetic Medicine 2006, 23, 1-12; Shichiri, et al., Lancet 1982, 7, 1129-1131, Hovorka, Nat. Rev. Endocrinol. 2011, 7, 385-395; Veiseh, et al., Nat. Rev. Drug Discov. 2014, 14, 45-57). Of note, three companies, Medtronic/MiniMed (Mastrototaro, Diabetes Technol. Ther. 2004, 2, 13-18), Dexcom (Girardin, et al., Clinical Biochemistry 2009, 42, 136-142), and Abbott, have competing technologies that allow continuous recording of BG fluctuations in interstitial fluid of the subcutaneous space (Gifford, Chem Phys Chem 2013, 14, 2032-2044). In contrast to SMBG, CGMs can capture BG fluctuations continuously and therefore enable complete tracking of blood glucose trends over time (Rodbard, Diabetes Technol. Ther. 2016, 18 Suppl 2, S23-S213).

However, problems with reliability and short-term noise or discordance, as well as requirements for multiple daily calibrations greatly limit the potential of CGMs, and the U.S. Food and Drug Administration (FDA) has not yet approved them as stand-alone monitoring devices (Rodbard, Diabetes Technol. Ther. 2016, 18 Suppl 2, S23-S213; Vaddiraju, et al., J. Diabetes Sch. Technol. 2010, 4, 1540-1562; Gerritsen, Diabetes Care 2000, 143; Nichols, et al., Chem. Rev. 2013, 113, 2528-2549). The implantation of CGM sensors creates significant noise or discordance during the initial (24 to 72-hour) recording period, yet the exact mechanism for this is still unclear (Gerritsen, Diabetes Care 2000, 143; Nichols, et al., Chem. Rev. 2013, 113, 2528-2549; Gerritsen, et al., Netherlands Journal of Medicine 1999, 54, 167-179; Novak, et al., J. Diabetes Sci. Technol. 2013, 7, 1547-1560). As a result, the FDA has approved the use of CGMs for up to 6 days post-implantation, but only alongside constant finger-prick blood recalibrations (i.e., four calibrations on the first day of use and one every 12 hours thereafter) (Rodbard, Diabetes Technol. Ther. 2016, 18 Suppl 2, S23-S213; Vaddiraju, et al., J. Diabetes Sch. Technol. 2010, 4, 1540-1562; Gerritsen, Diabetes Care 2000, 143; Nichols, et al., Chem. Rev. 2013, 113, 2528-2549; Jadviscokova, et al., Pap. Med. Fac. Univ. Palack, Olomouc, Czechoslov. 2007, 151, 263-266). The requirement for these frequent recalibrations, which is both wearisome and painful for users, also remains a problem with CGMs as inconsistent measurement sites and procedures, as well as varying patient health and/or stress status can lead to inaccurate and problematic BG measurements (Jadviscokova, et al., Pap. Med. Fac. Univ. Palack, Olomouc, Czechoslov. 2007, 151, 263-266; Boyne, et al., Diabetes 2003, 52, 2790-2794; Ellison, eg al., Diabetes Care 2002, 25, 961-964; Sylvain, et al., Am. J. Crit. Care 1995, 4, 44-48). Accordingly, there remains a need to develop CGMs with improved properties for continuously monitoring blood glucose levels in subjects that are at risk of developing hyperglycemia, which reduce and/or eliminate the afore-mentioned problems.

Therefore, it is an object of the present invention to provide CGMs with improved blood glucose monitoring properties.

It is another object of the present invention to provide CGMs that show reduced discordance between actual blood glucose levels and those detected using the CGMs during the first one to three days following implantation.

It is a further object of the present invention to provide CGMs in which all or part of the sensor electrode has been coated with zwitterionic polymer.

SUMMARY OF THE INVENTION

CGMs containing a sensor electrode that is partially or completely coated with one or more layers of a material containing zwitterionic polymers show significantly improved monitoring of blood glucose levels, as compared with corresponding CGMs having a sensor electrode lacking a zwitterionic polymer coating on its surface. Unlike currently commercially available CGMs, the CGMs with zwitterionic polymer coating on the surface of their sensor electrodes eliminate and/or show reduced discordance between actual blood glucose levels measured from blood and the sensor signal indicating blood glucose levels, during the first three days, after just one initial calibration using blood glucose levels from a strip test. This is a significant advance in the technology of CGMs, because diabetic patients monitoring their blood glucose levels with these CGMs only need to calibrate the CGMs once for the lifetime of the CMG after implantation, thereby avoiding the pain and discomfort associated with repeated finger-pricking to obtain actual blood glucose readings. Further, the CGMs give reliable blood glucose measurements during the first few days (e.g. first three days) post implantation without the need for repeated calibrations, a bottleneck that has largely prevented the FDA from approving CGMs as standalone devices for monitoring levels blood glucose.

Preferably, the zwitterionic polymer contains methacryloyloxyethyl phosphocholine, 2-(6,8-dimercaptooctanamido)ethyl methacrylate, 2-(5-(1,2-dithiolan-3-yl)pentanamido)ethyl methacrylate monomeric units, or a combination thereof. Preferably, one or more layers of polydopamine are formed on the surface of the sensor electrode, followed by conjugation of the zwitterionic polymer to the one or more layers of polydopamine. Preferably, the CGMs are implanted by subcutaneous insertion of the sensor electrode, and measures blood glucose indirectly from interstitial fluids.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A-1T show exemplary zwitterionic polymers that have been synthesized.

FIGS. 2A and 2B are line graphs of X-ray photoelectron spectroscopy (XPS) analysis showing surface properties of the sensor electrode of a CGM before (FIG. 2A) and after (FIG. 2B) application of a zwitterionic polymer.

FIG. 3 is a line graph showing in vitro glucose sensing of control and experimental CGMs. Experimental CGMs had a zwitterionic polymer coating on their sensor electrodes, while the control group did not.

FIGS. 4A-4D show linear regression of mice in vivo signal (lines) versus actual blood glucose levels (open circles). Signals were generated from two control (FIGS. 4A and 4B) and two experimental (FIGS. 4C and 4D) CGMs. Experimental CGMs had a zwitterionic polymer coating on their sensor electrodes, while the control group did not. The open circles show blood glucose (BG) levels measured with glucose test strips (eight times per day) on the first, second, and third days. The lines show CGM measured blood glucose levels with recalibration on the first, second, and third days.

FIGS. 5A-5D are line graphs showing mice in vivo non-recalibrated versus recalibrated (with all measured BG) data for both control and coated sensors during the entire recording period. Solid dots are actual blood glucose measurements.

FIGS. 6A-6D are line graphs showing comparisons between non-recalibrated glucose level versus blood glucose, and recalibrated versus blood glucose for both control and coated sensors.

FIG. 7 is a column graph showing the significance of various comparison methods of control and coated sensors (N=6 for each sensor group). Experiments repeated at least 2-3 times.

FIG. 8 is a column graph showing CGM biocompatibility in SKH1 mouse model. Quantification of IVIS inflammation signals from mice and statistical analysis showed that zwitterionic coating resulted in significantly reduced inflammation at all measured time points. * indicates statistically significant compared to the group “Control” at the level of p<0.05 using ANOVA followed by a post hoc test. n=5 mice/group.

FIGS. 9A-9F are column graphs showing NanoString representative expression analysis of inflammation markers (Cxcl15, Tnfsf5, Cxcl17, IL17b, Ccl20, and Cd19) on the days one and three following sensor implantation. Fold changes presented on a base 2 logarithmic scale. Experiments repeated at least 2-3 times. Nanostring performed once.

FIGS. 10A-10D are line graphs showing linear regression of non-human primates (NHPs) in vivo signal (lines) versus actual blood glucose levels (open circles) during a 3-day recording period, for both non-diabetic (FIGS. 10A and 10B) and diabetic (FIGS. 10C and 10D) NHPs.

FIGS. 11A-11D are line graphs showing NPH in vivo non-recalibrated versus recalibrated (using all measured BG) data for both non-diabetic and diabetic models. Solid dots are actual blood glucose measurements.

FIGS. 12A and 12B are column graphs showing the significance of various comparison methods of non-diabetic (FIG. 12A) and diabetic (FIG. 12B) NHP models.

FIGS. 13A and 13B are schematics of a bioelectrochemical reaction that occurs at the CGM electrode.

DETAILED DESCRIPTION OF THE INVENTION I. Definitions

“Continuous glucose monitor” or CGM, refers to a device that provides real-time levels of glucose in a bodily fluid within a subject, at time intervals such as from fractions of a second up to, for example, one minute, two minutes, five minutes, 10 minutes, 30 minutes, or one hour, or combinations thereof. A CGM can include a sensor electrode that continuously monitors glucose levels and an electronic processing component that is interconnected (wired or wireless) to the sensor electrode. Examples of CGMs include GUARDIAN REAL-TIME®, PARADIGM REAL-TIME®, PARADIGM VEO®, SEVEN®, SEVEN PLUS®, and FREESTYLE NAVIGATOR®.

“Beneficial effect,” as used herein, refers to any effect that is desired. In the context disclosed herein, beneficial effects include reduced discordance between an actual physical measurement and a signal generated to indicate levels of the measurement; lower inflammation; lower foreign body response; improved biocompatibility measured by less cell toxicity; reduced immune response or reaction; or a combination thereof. The actual physical measurement can be blood glucose levels.

“Biocompatible,” as used herein, refers to a substance or object, such as a CGM, that performs its desired function when introduced into an organism without inducing significant inflammatory response, immunogenicity, or cytotoxicity to native cells, tissues, or organs, or to cells, tissues, or organs introduced with the substance or object. For example, a biocompatible product is a product that performs its desired function when introduced into an organism without inducing significant inflammatory response, immunogenicity, or cytotoxicity to native cells, tissues, or organs. Biocompatibility, as used herein, can be quantified using the in vivo biocompatibility assay described below.

In this assay, a material or product is considered biocompatible if it produces, in a test of biocompatibility related to immune system reaction, less than 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10%, 8%, 6%, 5%, 4%, 3%, 2%, or 1% of the reaction, in the same test of biocompatibility, produced by a material or product the same as the test material or product except for a lack of a surface modification on the test material or product. Examples of useful biocompatibility tests include measuring and assessing cytotoxicity in cell culture, inflammatory response after implantation (such as by fluorescence detection of cathepsin activity; multiplexed NanoString gene expression analysis of inflammatory markers such as Cxcl15, Tnfsf18, Cxcl17, Ccl20, etc.), and immune system cells recruited to implant (for example, macrophages and neutrophils).

“Chemical modification” and related terms, as used herein, refers to chemical modification of the product. Generally, such chemical modification is by direct attachment, coupling, or adherence of a compound to the surface material of the product. Preferably, the chemical modification involves modification with one or more of the disclosed compounds. Chemical modification, as defined herein in the context of the disclosed products, can be accomplished at any time and in any manner, including, for example, synthesis or production of the modified form of the product or material when the product or material is formed, addition of the chemical modification after the final product or material is formed, or at any time in between. The terms “replaced,” “replace,” “modified,” “singularly modified,” “singular modification,” “multiply modified,” “multiple modifications,” “chemically modified,” “surface modified,” “modification,” “chemical modification,” “surface modification,” “substituted,” “substitution,” “derived from,” “based on,” or “derivatized,” and similar terms, as used herein to describe a structure, do not limit the structure to one made from a specific starting material or by a particular synthetic route. Except where specifically and expressly provided to the contrary, the terms refer to a structural property, regardless of how the structure was formed, and the structure is not limited to a structure made by any specific method.

“Coating” as used herein, refers to any temporary, semi-permanent or permanent layer, covering or surface. A coating can be applied as a gas, vapor, liquid, paste, semi-solid, or solid. In addition, a coating can be applied as a liquid and solidified into a hard coating. Elasticity can be engineered into coatings to accommodate pliability, e.g. swelling or shrinkage, of the substrate or surface to be coated.

“Contacting” as used herein in the context of coating refers to any way for coating a product, using one or more of the compounds disclosed herein, on a substrate such as a product. Contacting can include, but is not limited to, intraoperative dip-coating, spraying, wetting, immersing, dipping, painting, bonding or adhering, stepwise surface derivatization, or otherwise providing a substrate or surface with a compound. The compound can be covalently attached, non-covalently attached, or both, to the substrate or surface.

“Corresponding product” and “similar product,” as used herein, refers to a product that has, as far as is practical or possible, the same composition, structure, and construction as a reference product. The terms “corresponding” and “similar” can be used for the same meaning with any particular or subgroup of products or other materials described herein. For example, a “similar surface modification” refers a surface modification that has, as far as is practical or possible, the same composition, structure, and construction as a reference surface modification.

“Control corresponding product” and “control similar product,” as used herein, refers a product that has, as far as is practical or possible, the same composition, structure, and construction as a reference product except for one or more specified parameters. For example, a control corresponding product that lacks the chemical modification in reference to a chemically modified product refers to a product that has, as far as is practical or possible, the same composition, structure, and construction as a reference product except for the chemical modification. Generally, a product prior to chemical modification constitutes a control corresponding product to the chemically modified form of the product. The terms “control corresponding” and “control similar” can be used for the same meaning with any particular or subgroup of products or other materials described herein. For example, a “control similar surface modification” refers a surface modification that has, as far as is practical or possible, the same composition, structure, and construction as a reference surface modification except for one or more specified parameters. Components that are “control corresponding” or “control similar” relative to a reference component are useful as controls in assays assessing the effect of independent variables.

“Foreign body response” as used herein, refers to the immunological response of biological tissue to the presence of any foreign material in the tissue which can include protein adsorption, infiltration by immune cells or fibrosis.

“Hydrophilic” refers to molecules which have a greater affinity for, and thus solubility in, water as compared to organic solvents. The hydrophilicity of a compound can be quantified by measuring its partition coefficient between water (or a buffered aqueous solution) and a water-immiscible organic solvent, such as octanol, ethyl acetate, methylene chloride, or methyl tert-butyl ether. If after equilibration a greater concentration of the compound is present in the water than in the organic solvent, then the molecule is considered hydrophilic. “Hydrophilic” may also refer to a material that when applied to a surface, such as glass, forms a contact angle with water, which is less than the contact angle of water on a surface of glass without the material.

“Hydrophobic” refers to molecules which have a greater affinity for, and thus solubility in, organic solvents as compared to water. The hydrophobicity of a compound can be quantified by measuring its partition coefficient between water (or a buffered aqueous solution) and a water-immiscible organic solvent, such as octanol, ethyl acetate, methylene chloride, or methyl tert-butyl ether. If after equilibration a greater concentration of the compound is present in the organic solvent than in the water, then the molecule is considered hydrophobic. “Hydrophobic” may also refer to a material that when applied to a surface, such as glass, forms a contact angle with water, which is greater than the contact angle of water on a surface of glass without the material.

“Amphiphilic” refers to a property where a molecule has both a hydrophilic portion and a hydrophobic portion. Often, an amphiphilic compound has a hydrophilic portion covalently attached to a hydrophobic portion. In some forms, the hydrophilic portion is soluble in water, while the hydrophobic portion is insoluble in water. In addition, the hydrophilic and hydrophobic portions may have either a formal positive charge, or a formal negative charge. However, the overall they will be either hydrophilic or hydrophobic. The amphiphilic compound can be, but is not limited to, an amphiphilic polymer, such that the hydrophilic portion can be a hydrophilic polymer, and the hydrophobic portion can be a hydrophobic polymer.

“Implanting,” as used herein, refers to the insertion or grafting into the body of a subject a product or material.

“Neutral” refers to a monomer or monomeric unit within a polymer that does not contain a charged group covalently bound to another atom within the monomer or monomeric unit.

“Surface modification” and related terms, as used herein, refers to chemical modification of the surface of the product. Generally, such surface modification is by direct attachment, coupling, or adherence of a compound to the surface material of the product. Preferably, the surface modification involves modification with one or more of the disclosed compounds, e.g. zwitterionic polymers. Surface modification, as defined herein, can be accomplished by one skilled in the art, for example, by synthesis or production of the modified form of the product or material when the product or material is formed, addition of the chemical modification after the final product or material is formed, or at any time in between. Except where specifically provided to the contrary, the term “surface modification” refers to a structural property, regardless of how the structure was formed, and the structure is not limited to a structure made by any specific method.

In some forms, the zwitterionic polymers modifying the product can be present on the surface of the product, and are not present, or are not present in a significant amount, elsewhere in the product, e.g., on internal or interior surfaces. In some forms, at least 50, 60, 70, 80, 90, 95, or 99% of the zwitterionic polymers are present on the surface of the product. In some forms, the zwitterionic polymers are present on the exterior face of the surface of the product, and are not present, or not present in a significant amount, elsewhere in the product, e.g., on internal or interior surfaces. In some forms, at least 50, 60, 70, 80, 90, 95, or 99% of the zwitterionic polymers are present on the external face of the surface of the product.

As used herein, “signal” refers to a readout produced by a sensing part of a device, such as the sensor electrode of a CGM.

“Subject,” as used herein, includes human and veterinary subjects.

“Surface,” as used herein in the context of the disclosed products, refers to the exterior or outer boundary of a product. Generally, the surface of a product corresponds to the idealized surface of a three dimensional solid that is topological homeomorphic with the product. The surface can be an exterior surface or an interior surface. An exterior surface forms the outermost layer of a product or device. An interior surface surrounds an inner cavity of a product or device, such as the inner cavity of a tube. As an example, both the outside surface of a tube and the inside surface of a tube are part of the surface of the tube. However, internal surfaces of the product that are not in topological communication with the exterior surface, such as a tube with closed ends, can be excluded as the surface of a product. Preferred surfaces to be chemically modified are the outside surface and surfaces that can contact immune system components. Where the product is porous or has holes in its mean (idealized or surface), the internal faces of passages and holes would not be considered part of the surface of the product if its opening on the mean surface of the product is less than 1 μm.

“Zwitterion,” “zwitterionic,” and “zwitterionic monomer” are used interchangeably to refer to chemical compound, or a monomer or monomeric unit within a polymer, which contains one or more cationic groups and one or more anionic groups. Typically, the charges on the cationic and anionic groups are balanced, resulting in a monomer with zero net charge. However, it is not necessary that the charges on the cationic and anionic groups balance out.

“Zwitterionic polymer” refers to a polymer that contains at least a zwitterionic monomer, monomers with cationic and anionic groups on different monomer units, or a combination thereof. The zwitterionic polymers can be random copolymers, block copolymers, or a combination thereof.

“Biocompatible polymer” is used interchangeably with “zwitterionic polymer.”

“Substituted,” as used herein, refers to all permissible substituents of the compounds or functional groups described herein. In the broadest sense, the permissible substituents include acyclic and cyclic, branched and unbranched, carbocyclic and heterocyclic, aromatic and nonaromatic substituents of organic compounds. Illustrative substituents include, but are not limited to, halogens, hydroxyl groups, or any other organic groupings containing any number of carbon atoms, preferably 1-14 carbon atoms, and optionally include one or more heteroatoms such as oxygen, sulfur, or nitrogen grouping in linear, branched, or cyclic structural formats. Representative substituents include alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, phenyl, substituted phenyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, halo, hydroxyl, arylalkyl, substituted arylalkyl, alkoxy, substituted alkoxy, phenoxy, substituted phenoxy, aroxy, substituted aroxy, alkylthio, substituted alkylthio, phenylthio, substituted phenylthio, arylthio, substituted arylthio, cyano, isocyano, substituted isocyano, carbonyl, substituted carbonyl, carboxyl, substituted carboxyl, amino, substituted amino, amido, substituted amido, sulfonyl, substituted sulfonyl, sulfonic acid, phosphoryl, substituted phosphoryl, phosphonyl, substituted phosphonyl, polyaryl, substituted polyaryl, C₃-C₂₀ cyclic, substituted C₃-C₂₀ cyclic, heterocyclic, substituted heterocyclic, amino acid, poly(lactic-co-glycolic acid), peptide, and polypeptide groups. Such alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, phenyl, substituted phenyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, halo, hydroxyl, arylalkyl, substituted arylalkyl, alkoxy, substituted alkoxy, phenoxy, substituted phenoxy, aroxy, substituted aroxy, alkylthio, substituted alkylthio, phenylthio, substituted phenylthio, arylthio, substituted arylthio, cyano, isocyano, substituted isocyano, carbonyl, substituted carbonyl, carboxyl, substituted carboxyl, amino, substituted amino, amido, substituted amido, sulfonyl, substituted sulfonyl, sulfonic acid, phosphoryl, substituted phosphoryl, phosphonyl, substituted phosphonyl, polyaryl, substituted polyaryl, C₃-C₂₀ cyclic, substituted C₃-C₂₀ cyclic, heterocyclic, substituted heterocyclic, amino acid, poly(lactic-co-glycolic acid), peptide, and polypeptide groups can be further substituted.

Heteroatoms such as nitrogen may have hydrogen substituents and/or any permissible substituents of organic compounds described herein which satisfy the valences of the heteroatoms. It is understood that “substitution” or “substituted” includes the implicit proviso that such substitution is in accordance with permitted valence of the substituted atom and the substituent, and that the substitution results in a stable compound, i.e. a compound that does not spontaneously undergo transformation such as by rearrangement, cyclization, elimination, etc.

Except where specifically provided to the contrary, the term “substituted” refers to a structure, e.g., a chemical compound or a moiety on a larger chemical compound, regardless of how the structure was formed. The structure is not limited to a structure made by any specific method.

“Aryl,” as used herein, refers to C₅-C₂₆-membered aromatic, fused aromatic, fused heterocyclic, or biaromatic ring systems. Broadly defined, “aryl,” as used herein, includes 5-, 6-, 7-, 8-, 9-, 10-, 14-, 18-, and 24-membered single-ring aromatic groups, for example, benzene, naphthalene, anthracene, phenanthrene, chrysene, pyrene, corannulene, coronene, etc.

“Aryl” further encompasses polycyclic ring systems having two or more cyclic rings in which two or more carbons are common to two adjoining rings (i.e., “fused rings”) wherein at least one of the rings is aromatic, e.g., the other cyclic ring or rings can be cycloalkyls, cycloalkenyls, cycloalkynyls, aryls and/or heterocycles.

The term “substituted aryl” refers to an aryl group, wherein one or more hydrogen atoms on one or more aromatic rings are substituted with one or more substituents including, but not limited to, halogen, azide, alkyl, aralkyl, alkenyl, alkynyl, cycloalkyl, hydroxyl, alkoxy, carbonyl (such as a ketone, aldehyde, carboxyl, alkoxycarbonyl, formyl, or an acyl), silyl, ether, ester, thiocarbonyl (such as a thioester, a thioacetate, or a thioformate), alkoxyl, phosphoryl, phosphate, phosphonate, phosphinate, amino (or quarternized amino), amido, amidine, imine, cyano, nitro, azido, sulfhydryl, imino, alkylthio, sulfate, sulfonate, sulfamoyl, sulfoxide, sulfonamido, sulfonyl, heterocyclyl, alkylaryl, haloalkyl (such as CF₃, —CH₂—CF₃, —CCl₃), —CN, aryl, heteroaryl, and combinations thereof.

“Heterocycle,” “heterocyclic” and “heterocyclyl” are used interchangeably, and refer to a cyclic radical attached via a ring carbon or nitrogen atom of a monocyclic or bicyclic ring containing 3-10 ring atoms, and preferably from 5-6 ring atoms, consisting of carbon and one to four heteroatoms each selected from the group consisting of non-peroxide oxygen, sulfur, and N(Y) wherein Y is absent or is H, O, C₁-C₁₀ alkyl, phenyl or benzyl, and optionally containing 1-3 double bonds and optionally substituted with one or more substituents. Heterocyclyl are distinguished from heteroaryl by definition. Examples of heterocycles include, but are not limited to piperazinyl, piperidinyl, piperidonyl, 4-piperidonyl, dihydrofuro[2,3-b]tetrahydrofuran, morpholinyl, piperazinyl, piperidinyl, piperidonyl, 4-piperidonyl, piperonyl, pyranyl, 2H-pyrrolyl, 4H-quinolizinyl, quinuclidinyl, tetrahydrofuranyl, 6H-1,2,5-thiadiazinyl. Heterocyclic groups can optionally be substituted with one or more substituents as defined above for alkyl and aryl.

The term “heteroaryl” refers to C₅-C₂₆-membered aromatic, fused aromatic, biaromatic ring systems, or combinations thereof, in which one or more carbon atoms on one or more aromatic ring structures have been substituted with an heteroatom. Suitable heteroatoms include, but are not limited to, oxygen, sulfur, and nitrogen. Broadly defined, “heteroaryl,” as used herein, includes 5-, 6-, 7-, 8-, 9-, 10-, 14-, 18-, and 24-membered single-ring aromatic groups that may include from one to four heteroatoms, for example, pyrrole, furan, thiophene, imidazole, oxazole, thiazole, triazole, tetrazole, pyrazole, pyridine, pyrazine, pyridazine and pyrimidine, and the like. The heteroaryl group may also be referred to as “aryl heterocycles” or “heteroaromatics”. “Heteroaryl” further encompasses polycyclic ring systems having two or more rings in which two or more carbons are common to two adjoining rings (i.e., “fused rings”) wherein at least one of the rings is heteroaromatic, e.g., the other cyclic ring or rings can be cycloalkyls, cycloalkenyls, cycloalkynyls, aryls, heterocycles, or combinations thereof. Examples of heteroaryl rings include, but are not limited to, benzimidazolyl, benzofuranyl, benzothiofuranyl, benzothiophenyl, benzoxazolyl, benzoxazolinyl, benzthiazolyl, benztriazolyl, benztetrazolyl, benzisoxazolyl, benzisothiazolyl, benzimidazolinyl, carbazolyl, 4aH-carbazolyl, carbolinyl, chromanyl, chromenyl, cinnolinyl, decahydroquinolinyl, 2H,6H-1,5,2-dithiazinyl, furanyl, furazanyl, imidazolidinyl, imidazolinyl, imidazolyl, 1H-indazolyl, indolenyl, indolinyl, indolizinyl, indolyl, 3H-indolyl, isatinoyl, isobenzofuranyl, isochromanyl, isoindazolyl, isoindolinyl, isoindolyl, isoquinolinyl, isothiazolyl, isoxazolyl, methylenedioxyphenyl, naphthyridinyl, octahydroisoquinolinyl, 1,2,3-oxadiazolyl, 1,2,4-oxadiazolyl, 1,2,5-oxadiazolyl, 1,3,4-oxadiazolyl, oxazolidinyl, oxazolyl, oxindolyl, pyrimidinyl, phenanthridinyl, phenanthrolinyl, phenazinyl, phenothiazinyl, phenoxathinyl, phenoxazinyl, phthalazinyl, pteridinyl, purinyl, pyrazinyl, pyrazolidinyl, pyrazolinyl, pyrazolyl, pyridazinyl, pyridooxazole, pyridoimidazole, pyridothiazole, pyridinyl, pyridyl, pyrimidinyl, pyrrolidinyl, pyrrolinyl, pyrrolyl, quinazolinyl, quinolinyl, quinoxalinyl, tetrahydroisoquinolinyl, tetrahydroquinolinyl, tetrazolyl, 1,2,3-thiadiazolyl, 1,2,4-thiadiazolyl, 1,2,5-thiadiazolyl, 1,3,4-thiadiazolyl, thianthrenyl, thiazolyl, thienyl, thienothiazolyl, thienooxazolyl, thienoimidazolyl, thiophenyl and xanthenyl. One or more of the rings can be substituted as defined below for “substituted heteroaryl”.

The term “substituted heteroaryl” refers to a heteroaryl group in which one or more hydrogen atoms on one or more heteroaromatic rings are substituted with one or more substituents including, but not limited to, halogen, azide, alkyl, aralkyl, alkenyl, alkynyl, cycloalkyl, hydroxyl, alkoxy, carbonyl (such as a ketone, aldehyde, carboxyl, alkoxycarbonyl, formyl, or an acyl), silyl, ether, ester, thiocarbonyl (such as a thioester, a thioacetate, or a thioformate), alkoxyl, phosphoryl, phosphate, phosphonate, phosphinate, amino (or quarternized amino), amido, amidine, imine, cyano, nitro, azido, sulfhydryl, imino, alkylthio, sulfate, sulfonate, sulfamoyl, sulfoxide, sulfonamido, sulfonyl, heterocyclyl, alkylaryl, haloalkyl (such as CF₃, —CH₂—CF₃, —CCl₃), —CN, aryl, heteroaryl, and combinations thereof.

“Alkyl,” as used herein, refers to the radical of saturated aliphatic groups, including straight-chain alkyl, alkenyl, or alkynyl groups, branched-chain alkyl, cycloalkyl (alicyclic), alkyl substituted cycloalkyl groups, and cycloalkyl substituted alkyl. In preferred embodiments, a straight chain or branched chain alkyl has 30 or fewer carbon atoms in its backbone (e.g., C₁-C₃₀ for straight chains, C₃-C₃₀ for branched chains), preferably 20 or fewer, more preferably 15 or fewer, most preferably 10 or fewer. Likewise, preferred cycloalkyls have from 3-10 carbon atoms in their ring structure, and more preferably have 5, 6 or 7 carbons in the ring structure. The term “alkyl” (or “lower alkyl”) as used throughout the specification, examples, and claims is intended to include both “unsubstituted alkyls” and “substituted alkyls,” the latter of which refers to alkyl moieties having one or more substituents replacing a hydrogen on one or more carbons of the hydrocarbon backbone. Such substituents include, but are not limited to, halogen, hydroxyl, carbonyl (such as a carboxyl, alkoxycarbonyl, formyl, or an acyl), thiocarbonyl (such as a thioester, a thioacetate, or a thioformate), alkoxyl, phosphoryl, phosphate, phosphonate, a phosphinate, amino, amido, amidine, imine, cyano, nitro, azido, sulfhydryl, alkylthio, sulfate, sulfonate, sulfamoyl, sulfoxide, sulfonamido, sulfonyl, heterocyclyl, aralkyl, or an aromatic or heteroaromatic moiety.

Unless the number of carbons is otherwise specified, “lower alkyl” as used herein means an alkyl group, as defined above, but having from one to ten carbons, more preferably from one to six carbon atoms in its backbone structure. Likewise, “lower alkenyl” and “lower alkynyl” have similar chain lengths. Throughout the application, preferred alkyl groups are lower alkyls. In preferred embodiments, a substituent designated herein as alkyl is a lower alkyl.

“Alkyl” includes one or more substitutions at one or more carbon atoms of the hydrocarbon radical as well as heteroalkyls. Suitable substituents include, but are not limited to, halogens, such as fluorine, chlorine, bromine, or iodine; hydroxyl; —NRR′, wherein R and R′ are independently hydrogen, alkyl, or aryl, and wherein the nitrogen atom is optionally quaternized; —SR, wherein R is hydrogen, alkyl, or aryl; —CN; —NO₂; —COOH; carboxylate; —COR, —COOR, or —CON(R)₂, wherein R is hydrogen, alkyl, or aryl; azide, aralkyl, alkoxyl, imino, phosphonate, phosphinate, silyl, ether, sulfonyl, sulfonamido, heterocyclyl, aromatic or heteroaromatic moieties, haloalkyl (such as —CF₃, —CH₂—CF₃, —CCl₃); —CN; —NCOCOCH₂CH₂, —NCOCOCHCH; —NCS; and combinations thereof.

It will be understood by those skilled in the art that the moieties substituted on the hydrocarbon chain can themselves be substituted, if appropriate. For instance, the substituents of a substituted alkyl may include halogen, hydroxy, nitro, thiols, amino, azido, imino, amido, phosphoryl (including phosphonate and phosphinate), sulfonyl (including sulfate, sulfonamido, sulfamoyl, sulfoxide, and sulfonate), and silyl groups, as well as ethers, alkylthios, carbonyls (including ketones, aldehydes, carboxylates, and esters), haloalkyls, —CN and the like. Cycloalkyls can be substituted in the same manner.

The terms “alkenyl” and “alkynyl” refer to unsaturated aliphatic groups analogous in length and possible substitution to the alkyls described above, but that contain at least one double or triple bond, respectively.

The term “substituted alkenyl” refers to alkenyl moieties having one or more substituents replacing one or more hydrogen atoms on one or more carbons of the hydrocarbon backbone. Such substituents include, but are not limited to, halogen, azide, alkyl, aralkyl, alkenyl, alkynyl, cycloalkyl, hydroxyl, carbonyl (such as a carboxyl, alkoxycarbonyl, formyl, or an acyl), silyl, ether, ester, thiocarbonyl (such as a thioester, a thioacetate, or a thioformate), alkoxyl, phosphoryl, phosphate, phosphonate, phosphinate, amino (or quarternized amino), amido, amidine, imine, cyano, nitro, azido, sulfhydryl, alkylthio, sulfate, sulfonate, sulfamoyl, sulfoxide, sulfonamido, sulfonyl, heterocyclyl, alkylaryl, haloalkyl, —CN, aryl, heteroaryl, and combinations thereof.

The term “substituted alkynyl” refers to alkynyl moieties having one or more substituents replacing one or more hydrogen atoms on one or more carbons of the hydrocarbon backbone. Such substituents include, but are not limited to, halogen, azide, alkyl, aralkyl, alkenyl, alkynyl, cycloalkyl, hydroxyl, carbonyl (such as a carboxyl, alkoxycarbonyl, formyl, or an acyl), silyl, ether, ester, thiocarbonyl (such as a thioester, a thioacetate, or a thioformate), alkoxyl, phosphoryl, phosphate, phosphonate, phosphinate, amino (or quarternized amino), amido, amidine, imine, cyano, nitro, azido, sulfhydryl, alkylthio, sulfate, sulfonate, sulfamoyl, sulfoxide, sulfonamido, sulfonyl, heterocyclyl, alkylaryl, haloalkyl, —CN, aryl, heteroaryl, and combinations thereof.

The term “phenyl” is art recognized, and refers to the aromatic moiety —C₆H₅, i.e., a benzene ring without one hydrogen atom.

The term “substituted phenyl” refers to a phenyl group, as defined above, having one or more substituents replacing one or more hydrogen atoms on one or more carbons of the phenyl ring. Such substituents include, but are not limited to, halogen, azide, alkyl, aralkyl, alkenyl, alkynyl, cycloalkyl, hydroxyl, carbonyl (such as a carboxyl, alkoxycarbonyl, formyl, or an acyl), silyl, ether, ester, thiocarbonyl (such as a thioester, a thioacetate, or a thioformate), alkoxyl, phosphoryl, phosphate, phosphonate, phosphinate, amino (or quarternized amino), amido, amidine, imine, cyano, nitro, azido, sulfhydryl, alkylthio, sulfate, sulfonate, sulfamoyl, sulfoxide, sulfonamido, sulfonyl, heterocyclyl, alkylaryl, haloalkyl, —CN, aryl, heteroaryl, and combinations thereof.

“Amino” and “Amine,” as used herein, are art-recognized and refer to both substituted and unsubstituted amines, e.g., a moiety that can be represented by the general formula:

wherein, R, R′, and R″ each independently represent a hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted carbonyl, —(CH₂)_(m)—R′″, or R and R′ taken together with the N atom to which they are attached complete a heterocycle having from 3 to 14 atoms in the ring structure; R″ represents a hydroxy group, substituted or unsubstituted carbonyl group, an aryl, a cycloalkyl ring, a cycloalkenyl ring, a heterocycle, or a polycycle; and m is zero or an integer ranging from 1 to 8. In preferred embodiments, only one of R and R′ can be a carbonyl, e.g., R and R′ together with the nitrogen do not form an imide. In preferred embodiments, R and R′ (and optionally R″) each independently represent a hydrogen atom, substituted or unsubstituted alkyl, a substituted or unsubstituted alkenyl, or —(CH₂)_(m)—R′″. Thus, the term ‘alkylamine’ as used herein refers to an amine group, as defined above, having a substituted or unsubstituted alkyl attached thereto (i.e. at least one of R, R′, or R″ is an alkyl group).

“Carbonyl,” as used herein, is art-recognized and includes such moieties as can be represented by the general formula:

wherein X is a bond, or represents an oxygen or a sulfur, and R represents a hydrogen, a substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted heterocyclyl, substituted or unsubstituted alkylaryl, substituted or unsubstituted arylalkyl, substituted or unsubstituted aryl, or substituted or unsubstituted heteroaryl, —(CH₂)_(m)—R″, or a pharmaceutical acceptable salt, R′ represents a hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted heterocyclyl, substituted or unsubstituted alkylaryl, substituted or unsubstituted arylalkyl, substituted or unsubstituted aryl, or substituted or unsubstituted heteroaryl or —(CH₂)_(m)—R″; R″ represents a hydroxy group, substituted or unsubstituted carbonyl group, an aryl, a cycloalkyl ring, a cycloalkenyl ring, a heterocycle, or a polycycle; and m is zero or an integer ranging from 1 to 8. Where X is oxygen and R is defines as above, the moiety is also referred to as a carboxyl group. When X is oxygen and R is hydrogen, the formula represents a ‘carboxylic acid’. Where X is oxygen and R′ is hydrogen, the formula represents a ‘formate’. Where X is oxygen and R or R′ is not hydrogen, the formula represents an “ester”. In general, where the oxygen atom of the above formula is replaced by a sulfur atom, the formula represents a ‘thiocarbonyl’ group. Where X is sulfur and R or R′ is not hydrogen, the formula represents a ‘thioester.’ Where X is sulfur and R is hydrogen, the formula represents a ‘thiocarboxylic acid.’ Where X is sulfur and R′ is hydrogen, the formula represents a ‘thioformate.’ Where X is a bond and R is not hydrogen, the above formula represents a ‘ketone.’ Where X is a bond and R is hydrogen, the above formula represents an ‘aldehyde.’

The term “substituted carbonyl” refers to a carbonyl, as defined above, wherein one or more hydrogen atoms in R, R′ or a group to which the moiety

is attached, are independently substituted. Such substituents include, but are not limited to, halogen, azide, alkyl, aralkyl, alkenyl, alkynyl, cycloalkyl, hydroxyl, carbonyl (such as a carboxyl, alkoxycarbonyl, formyl, or an acyl), silyl, ether, ester, thiocarbonyl (such as a thioester, a thioacetate, or a thioformate), alkoxyl, phosphoryl, phosphate, phosphonate, phosphinate, amino (or quarternized amino), amido, amidine, imine, cyano, nitro, azido, sulfhydryl, alkylthio, sulfate, sulfonate, sulfamoyl, sulfoxide, sulfonamido, sulfonyl, heterocyclyl, alkylaryl, haloalkyl, —CN, aryl, heteroaryl, and combinations thereof.

The term “carboxyl” is as defined above for the formula

and is defined more specifically by the formula —R^(iv)COOH, wherein R^(iv) is an alkyl, alkenyl, alkynyl, cycloalkyl, heterocyclyl, alkylaryl, arylalkyl, aryl, or heteroaryl. In preferred embodiments, a straight chain or branched chain alkyl, alkenyl, and alkynyl have 30 or fewer carbon atoms in its backbone (e.g., C₁-C₃₀ for straight chain alkyl, C₃-C₃₀ for branched chain alkyl, C₂-C₃₀ for straight chain alkenyl and alkynyl, C₃-C₃₀ for branched chain alkenyl and alkynyl), preferably 20 or fewer, more preferably 15 or fewer, most preferably 10 or fewer. Likewise, preferred cycloalkyls, heterocyclyls, aryls and heteroaryls have from 3-10 carbon atoms in their ring structure, and more preferably have 5, 6 or 7 carbons in the ring structure.

The term “substituted carboxyl” refers to a carboxyl, as defined above, wherein one or more hydrogen atoms in R^(iv) are substituted. Such substituents include, but are not limited to, halogen, azide, alkyl, aralkyl, alkenyl, alkynyl, cycloalkyl, hydroxyl, carbonyl (such as a carboxyl, alkoxycarbonyl, formyl, or an acyl), silyl, ether, ester, thiocarbonyl (such as a thioester, a thioacetate, or a thioformate), alkoxyl, phosphoryl, phosphate, phosphonate, phosphinate, amino (or quarternized amino), amido, amidine, imine, cyano, nitro, azido, sulfhydryl, alkylthio, sulfate, sulfonate, sulfamoyl, sulfoxide, sulfonamido, sulfonyl, heterocyclyl, alkylaryl, haloalkyl, —CN, aryl, heteroaryl, and combinations thereof.

“Heteroalkyl,” as used herein, refers to straight or branched chain, or cyclic carbon-containing radicals, or combinations thereof, containing at least one heteroatom. Suitable heteroatoms include, but are not limited to, 0, N, Si, P and S, wherein the nitrogen, phosphorous and sulfur atoms are optionally oxidized, and the nitrogen heteroatom is optionally quaternized.

Examples of saturated hydrocarbon radicals include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, t-butyl, isobutyl, sec-butyl, cyclohexyl, (cyclohexyl)methyl, cyclopropylmethyl, and homologs and isomers of, for example, n-pentyl, n-hexyl, n-heptyl, n-octyl. Examples of unsaturated alkyl groups include, but are not limited to, vinyl, 2-propenyl, crotyl, 2-isopentenyl, 2-(butadienyl), 2,4-pentadienyl, 3-(1,4-pentadienyl), ethynyl, 1- and 3-propynyl, and 3-butynyl.

The terms “alkoxyl” or “alkoxy,” “aroxy” or “aryloxy,” generally describe compounds represented by the formula —OR^(v), wherein R^(v) includes, but is not limited to, substituted or unsubstituted alkyl, alkenyl, alkynyl, cycloalkyl, heterocyclyl, cycloalkenyl, heterocycloalkenyl, aryl, heteroaryl, arylalkyl, heteroalkyls, alkylaryl, alkylheteroaryl.

The terms “alkoxyl” or “alkoxy” as used herein refer to an alkyl group, as defined above, having an oxygen radical attached thereto. Representative alkoxyl groups include methoxy, ethoxy, propyloxy, tert-butoxy and the like. An “ether” is two hydrocarbons covalently linked by an oxygen. Accordingly, the substituent of an alkyl that renders that alkyl an ether is or resembles an alkoxyl, such as can be represented by one of —O— alkyl, —O-alkenyl, and —O-alkynyl. The term alkoxy also includes cycloalkyl, heterocyclyl, cycloalkenyl, heterocycloalkenyl, and arylalkyl having an oxygen radical attached to at least one of the carbon atoms, as valency permits.

The term “substituted alkoxy” refers to an alkoxy group having one or more substituents replacing one or more hydrogen atoms on one or more carbons of the alkoxy backbone. Such substituents include, but are not limited to, halogen, azide, alkyl, aralkyl, alkenyl, alkynyl, cycloalkyl, hydroxyl, carbonyl (such as a carboxyl, alkoxycarbonyl, formyl, or an acyl), silyl, ether, ester, thiocarbonyl (such as a thioester, a thioacetate, or a thioformate), alkoxyl, phosphoryl, phosphate, phosphonate, phosphinate, amino (or quarternized amino), amido, amidine, imine, cyano, nitro, azido, sulfhydryl, alkylthio, sulfate, sulfonate, sulfamoyl, sulfoxide, sulfonamido, sulfonyl, heterocyclyl, alkylaryl, haloalkyl, —CN, aryl, heteroaryl, and combinations thereof.

The term “phenoxy” is art recognized, and refers to a compound of the formula —OR^(v) wherein R^(v) is (i.e., —O—C₆H₅). One of skill in the art recognizes that a phenoxy is a species of the aroxy genus.

The term “substituted phenoxy” refers to a phenoxy group, as defined above, having one or more substituents replacing one or more hydrogen atoms on one or more carbons of the phenyl ring. Such substituents include, but are not limited to, halogen, azide, alkyl, aralkyl, alkenyl, alkynyl, cycloalkyl, hydroxyl, carbonyl (such as a carboxyl, alkoxycarbonyl, formyl, or an acyl), silyl, ether, ester, thiocarbonyl (such as a thioester, a thioacetate, or a thioformate), alkoxyl, phosphoryl, phosphate, phosphonate, phosphinate, amino (or quarternized amino), amido, amidine, imine, cyano, nitro, azido, sulfhydryl, alkylthio, sulfate, sulfonate, sulfamoyl, sulfoxide, sulfonamido, sulfonyl, heterocyclyl, alkylaryl, haloalkyl, —CN, aryl, heteroaryl, and combinations thereof.

The terms “aroxy” and “aryloxy,” as used interchangeably herein, are represented by —O-aryl or —O-heteroaryl, wherein aryl and heteroaryl are as defined herein.

The terms “substituted aroxy” and “substituted aryloxy,” as used interchangeably herein, represent —O-aryl or —O-heteroaryl, having one or more substituents replacing one or more hydrogen atoms on one or more ring atoms of the aryl and heteroaryl, as defined herein. Such substituents include, but are not limited to, halogen, azide, alkyl, aralkyl, alkenyl, alkynyl, cycloalkyl, hydroxyl, carbonyl (such as a carboxyl, alkoxycarbonyl, formyl, or an acyl), silyl, ether, ester, thiocarbonyl (such as a thioester, a thioacetate, or a thioformate), alkoxyl, phosphoryl, phosphate, phosphonate, phosphinate, amino (or quarternized amino), amido, amidine, imine, cyano, nitro, azido, sulfhydryl, alkylthio, sulfate, sulfonate, sulfamoyl, sulfoxide, sulfonamido, sulfonyl, heterocyclyl, alkylaryl, haloalkyl, —CN, aryl, heteroaryl, and combinations thereof.

The term “alkylthio” refers to an alkyl group, as defined above, having a sulfur radical attached thereto. The “alkylthio” moiety is represented by —S-alkyl. Representative alkylthio groups include methylthio, ethylthio, and the like. The term “alkylthio” also encompasses cycloalkyl groups having a sulfur radical attached thereto.

The term “substituted alkylthio” refers to an alkylthio group having one or more substituents replacing one or more hydrogen atoms on one or more carbon atoms of the alkylthio backbone. Such substituents include, but are not limited to, halogen, azide, alkyl, aralkyl, alkenyl, alkynyl, cycloalkyl, hydroxyl, carbonyl (such as a carboxyl, alkoxycarbonyl, formyl, or an acyl), silyl, ether, ester, thiocarbonyl (such as a thioester, a thioacetate, or a thioformate), alkoxyl, phosphoryl, phosphate, phosphonate, phosphinate, amino (or quarternized amino), amido, amidine, imine, cyano, nitro, azido, sulfhydryl, alkylthio, sulfate, sulfonate, sulfamoyl, sulfoxide, sulfonamido, sulfonyl, heterocyclyl, alkylaryl, haloalkyl, —CN, aryl, heteroaryl, and combinations thereof.

The term “phenylthio” is art recognized, and refers to —S—C₆H₅, i.e., a phenyl group attached to a sulfur atom.

The term “substituted phenylthio” refers to a phenylthio group, as defined above, having one or more substituents replacing a hydrogen on one or more carbons of the phenyl ring. Such substituents include, but are not limited to, halogen, azide, alkyl, aralkyl, alkenyl, alkynyl, cycloalkyl, hydroxyl, carbonyl (such as a carboxyl, alkoxycarbonyl, formyl, or an acyl), silyl, ether, ester, thiocarbonyl (such as a thioester, a thioacetate, or a thioformate), alkoxyl, phosphoryl, phosphate, phosphonate, phosphinate, amino (or quarternized amino), amido, amidine, imine, cyano, nitro, azido, sulfhydryl, alkylthio, sulfate, sulfonate, sulfamoyl, sulfoxide, sulfonamido, sulfonyl, heterocyclyl, alkylaryl, haloalkyl, —CN, aryl, heteroaryl, and combinations thereof.

“Arylthio” refers to —S-aryl or —S-heteroaryl groups, wherein aryl and heteroaryl as defined herein.

The term “substituted arylthio” represents —S-aryl or —S-heteroaryl, having one or more substituents replacing a hydrogen atom on one or more ring atoms of the aryl and heteroaryl rings as defined herein. Such substituents include, but are not limited to, halogen, azide, alkyl, aralkyl, alkenyl, alkynyl, cycloalkyl, hydroxyl, carbonyl (such as a carboxyl, alkoxycarbonyl, formyl, or an acyl), silyl, ether, ester, thiocarbonyl (such as a thioester, a thioacetate, or a thioformate), alkoxyl, phosphoryl, phosphate, phosphonate, phosphinate, amino (or quarternized amino), amido, amidine, imine, cyano, nitro, azido, sulfhydryl, alkylthio, sulfate, sulfonate, sulfamoyl, sulfoxide, sulfonamido, sulfonyl, heterocyclyl, alkylaryl, haloalkyl, —CN, aryl, heteroaryl, and combinations thereof.

“Arylalkyl,” as used herein, refers to an alkyl group that is substituted with a substituted or unsubstituted aryl or heteroaryl group.

“Alkylaryl,” as used herein, refers to an aryl group (e.g., an aromatic or hetero aromatic group), substituted with a substituted or unsubstituted alkyl group.

The terms “amide” or “amido” are used interchangeably, refer to both “unsubstituted amido” and “substituted amido” and are represented by the general formula:

wherein, E is absent, or E is substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aralkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted heterocyclyl, wherein independently of E, R and R′ each independently represent a hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted carbonyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted heterocyclyl, substituted or unsubstituted alkylaryl, substituted or unsubstituted arylalkyl, substituted or unsubstituted aryl, or substituted or unsubstituted heteroaryl, —(CH₂)_(m)—R′″, or R and R′ taken together with the N atom to which they are attached complete a heterocycle having from 3 to 14 atoms in the ring structure; R′″ represents a hydroxy group, substituted or unsubstituted carbonyl group, an aryl, a cycloalkyl ring, a cycloalkenyl ring, a heterocycle, or a polycycle; and m is zero or an integer ranging from 1 to 8. In preferred embodiments, only one of R and R′ can be a carbonyl, e.g., R and R′ together with the nitrogen do not form an imide. In preferred embodiments, R and R′ each independently represent a hydrogen atom, substituted or unsubstituted alkyl, a substituted or unsubstituted alkenyl, or —(CH₂)_(m)—R′″. When E is oxygen, a carbamate is formed. The carbamate cannot be attached to another chemical species, such as to form an oxygen-oxygen bond, or other unstable bonds, as understood by one of ordinary skill in the art.

The term “sulfonyl” is represented by the formula

wherein E is absent, or E is alkyl, alkenyl, alkynyl, aralkyl, alkylaryl, cycloalkyl, aryl, heteroaryl, heterocyclyl, wherein independently of E, R represents a hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted amine, substituted or unsubstituted cycloalkyl, substituted or unsubstituted heterocyclyl, substituted or unsubstituted alkylaryl, substituted or unsubstituted arylalkyl, substituted or unsubstituted aryl, or substituted or unsubstituted heteroaryl, —(CH₂)_(m)—R′″, or E and R taken together with the S atom to which they are attached complete a heterocycle having from 3 to 14 atoms in the ring structure; R′″ represents a hydroxy group, substituted or unsubstituted carbonyl group, an aryl, a cycloalkyl ring, a cycloalkenyl ring, a heterocycle, or a polycycle; and m is zero or an integer ranging from 1 to 8. In preferred embodiments, only one of E and R can be substituted or unsubstituted amine, to form a “sulfonamide” or “sulfonamido.” The substituted or unsubstituted amine is as defined above.

The term “substituted sulfonyl” represents a sulfonyl in which E, R, or both, are independently substituted. Such substituents include, but are not limited to, halogen, azide, alkyl, aralkyl, alkenyl, alkynyl, cycloalkyl, hydroxyl, carbonyl (such as a carboxyl, alkoxycarbonyl, formyl, or an acyl), silyl, ether, ester, thiocarbonyl (such as a thioester, a thioacetate, or a thioformate), alkoxyl, phosphoryl, phosphate, phosphonate, phosphinate, amino (or quarternized amino), amido, amidine, imine, cyano, nitro, azido, sulfhydryl, alkylthio, sulfate, sulfonate, sulfamoyl, sulfoxide, sulfonamido, sulfonyl, heterocyclyl, alkylaryl, haloalkyl, —CN, aryl, heteroaryl, and combinations thereof.

The term “sulfonic acid” refers to a sulfonyl, as defined above, wherein R is hydroxyl, and E is absent, or E is substituted or unsubstituted cycloalkyl, substituted or unsubstituted heterocyclyl, substituted or unsubstituted alkylaryl, substituted or unsubstituted arylalkyl, substituted or unsubstituted aryl, or substituted or unsubstituted heteroaryl.

The term “sulfate” refers to a sulfonyl, as defined above, wherein E is absent, oxygen, alkoxy, aroxy, substituted alkoxy or substituted aroxy, as defined above, and R is independently hydroxyl, alkoxy, aroxy, substituted alkoxy or substituted aroxy, as defined above. When E is oxygen, the sulfate cannot be attached to another chemical species, such as to form an oxygen-oxygen bond, or other unstable bonds, as understood by one of ordinary skill in the art.

The term “sulfonate” refers to a sulfonyl, as defined above, wherein E is oxygen, alkoxy, aroxy, substituted alkoxy or substituted aroxy, as defined above, and R is independently hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted amine, substituted or unsubstituted cycloalkyl, substituted or unsubstituted heterocyclyl, substituted or unsubstituted alkylaryl, substituted or unsubstituted arylalkyl, substituted or unsubstituted aryl, or substituted or unsubstituted heteroaryl, —(CH₂)_(m)—R′″, R′″ represents a hydroxy group, substituted or unsubstituted carbonyl group, an aryl, a cycloalkyl ring, a cycloalkenyl ring, a heterocycle, or a polycycle; and m is zero or an integer ranging from 1 to 8. When E is oxygen, sulfonate cannot be attached to another chemical species, such as to form an oxygen-oxygen bond, or other unstable bonds, as understood by one of ordinary skill in the art.

The term “sulfamoyl” refers to a sulfonamide or sulfonamide represented by the formula

wherein E is absent, or E is substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aralkyl, substituted or unsubstituted alkylaryl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted heterocyclyl, wherein independently of E, R and R′ each independently represent a hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted carbonyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted heterocyclyl, substituted or unsubstituted alkylaryl, substituted or unsubstituted arylalkyl, substituted or unsubstituted aryl, or substituted or unsubstituted heteroaryl, —(CH₂)_(m)—R′″, or R and R′ taken together with the N atom to which they are attached complete a heterocycle having from 3 to 14 atoms in the ring structure; R′″ represents a hydroxy group, substituted or unsubstituted carbonyl group, an aryl, a cycloalkyl ring, a cycloalkenyl ring, a heterocycle, or a polycycle; and m is zero or an integer ranging from 1 to 8. In preferred embodiments, only one of R and R′ can be a carbonyl, e.g., R and R′ together with the nitrogen do not form an imide.

The term “sulfoxide” is represented by the formula

wherein E is absent, or E is alkyl, alkenyl, alkynyl, aralkyl, alkylaryl, cycloalkyl, aryl, heteroaryl, heterocyclyl, wherein independently of E, R represents a hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted amine, substituted or unsubstituted cycloalkyl, substituted or unsubstituted heterocyclyl, substituted or unsubstituted alkylaryl, substituted or unsubstituted arylalkyl, substituted or unsubstituted aryl, or substituted or unsubstituted heteroaryl, —(CH₂)_(m)—R′″, or E and R taken together with the S atom to which they are attached complete a heterocycle having from 3 to 14 atoms in the ring structure; R′″ represents a hydroxy group, substituted or unsubstituted carbonyl group, an aryl, a cycloalkyl ring, a cycloalkenyl ring, a heterocycle, or a polycycle; and m is zero or an integer ranging from 1 to 8.

The term “phosphonyl” is represented by the formula

wherein E is absent, or E is substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aralkyl, substituted or unsubstituted alkylaryl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted heterocyclyl, wherein, independently of E, R^(vi) and R^(vii) are independently hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted carbonyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted heterocyclyl, substituted or unsubstituted alkylaryl, substituted or unsubstituted arylalkyl, substituted or unsubstituted aryl, or substituted or unsubstituted heteroaryl, —(CH₂)_(m)—R′″, or R and R′ taken together with the P atom to which they are attached complete a heterocycle having from 3 to 14 atoms in the ring structure; R′″ represents a hydroxy group, substituted or unsubstituted carbonyl group, an aryl, a cycloalkyl ring, a cycloalkenyl ring, a heterocycle, or a polycycle; and m is zero or an integer ranging from 1 to 8.

The term “substituted phosphonyl” represents a phosphonyl in which E, R^(vi) and R^(vii) are independently substituted. Such substituents include, but are not limited to, halogen, azide, alkyl, aralkyl, alkenyl, alkynyl, cycloalkyl, hydroxyl, carbonyl (such as a carboxyl, alkoxycarbonyl, formyl, or an acyl), silyl, ether, ester, thiocarbonyl (such as a thioester, a thioacetate, or a thioformate), alkoxyl, phosphoryl, phosphate, phosphonate, phosphinate, amino (or quarternized amino), amido, amidine, imine, cyano, nitro, azido, sulfhydryl, alkylthio, sulfate, sulfonate, sulfamoyl, sulfoxide, sulfonamido, sulfonyl, heterocyclyl, alkylaryl, haloalkyl, —CN, aryl, heteroaryl, and combinations thereof.

The term “phosphoryl” defines a phosphonyl in which E is absent, oxygen, alkoxy, aroxy, substituted alkoxy or substituted aroxy, as defined above, and independently of E, R^(vi) and R^(vii) are independently hydroxyl, alkoxy, aroxy, substituted alkoxy or substituted aroxy, as defined above. When E is oxygen, the phosphoryl cannot be attached to another chemical species, such as to form an oxygen-oxygen bond, or other unstable bonds, as understood by one of ordinary skill in the art. When E, R^(vi) and R^(vii) are substituted, the substituents include, but are not limited to, halogen, azide, alkyl, aralkyl, alkenyl, alkynyl, cycloalkyl, hydroxyl, carbonyl (such as a carboxyl, alkoxycarbonyl, formyl, or an acyl), silyl, ether, ester, thiocarbonyl (such as a thioester, a thioacetate, or a thioformate), alkoxyl, phosphoryl, phosphate, phosphonate, phosphinate, amino (or quarternized amino), amido, amidine, imine, cyano, nitro, azido, sulfhydryl, alkylthio, sulfate, sulfonate, sulfamoyl, sulfoxide, sulfonamido, sulfonyl, heterocyclyl, alkylaryl, haloalkyl, —CN, aryl, heteroaryl, and combinations thereof.

The term “polyaryl” refers to a chemical moiety that includes two or more aryls, heteroaryls, and combinations thereof. The aryls, heteroaryls, and combinations thereof, are fused, or linked via a single bond, ether, ester, carbonyl, amide, sulfonyl, sulfonamide, alkyl, azo, and combinations thereof.

The term “substituted polyaryl” refers to a polyaryl in which one or more of the aryls, heteroaryls are substituted, with one or more substituents including, but not limited to, halogen, azide, alkyl, aralkyl, alkenyl, alkynyl, cycloalkyl, hydroxyl, carbonyl (such as a carboxyl, alkoxycarbonyl, formyl, or an acyl), silyl, ether, ester, thiocarbonyl (such as a thioester, a thioacetate, or a thioformate), alkoxyl, phosphoryl, phosphate, phosphonate, phosphinate, amino (or quarternized amino), amido, amidine, imine, cyano, nitro, azido, sulfhydryl, alkylthio, sulfate, sulfonate, sulfamoyl, sulfoxide, sulfonamido, sulfonyl, heterocyclyl, alkylaryl, haloalkyl, —CN, aryl, heteroaryl, and combinations thereof.

The term “C₃-C₂₀ cyclic” refers to a substituted or unsubstituted cycloalkyl, substituted or unsubstituted cycloalkenyl, substituted or unsubstituted cycloalkynyl, substituted or unsubstituted heterocyclyl that have from three to 20 carbon atoms, as geometric constraints permit. The cyclic structures are formed from single or fused ring systems. The substituted cycloalkyls, cycloalkenyls, cycloalkynyls and heterocyclyls are substituted as defined above for the alkyls, alkenyls, alkynyls and heterocyclyls, respectively.

The terms “hydroxyl” and “hydroxy” are used interchangeably and are represented by —OH.

The terms “thiol” and “sulfhydryl” are used interchangeably and are represented by —SH.

The term “oxo” refers to ═O bonded to a carbon atom.

The terms “cyano” and “nitrile” are used interchangeably to refer to —CN. The term “nitro” refers to —NO₂.

The term “phosphate” refers to —O—PO₃.

The term “azide” or “azido” are used interchangeably to refer to —N₃. The term “substituted C₁-C_(x) alkyl” refers to alkyl groups having from one to x carbon atoms, wherein at least one carbon atom is substituted, wherein “x” is an integer from one to ten. The term “unsubstituted C₁-C_(x) alkyl” refers to alkyl groups having from one to x carbon atoms that are not substituted, wherein “x” is an integer from one to ten.

The term “substituted C₁-C_(x) alkylene” refers to alkylene groups having from one to x carbon atoms, wherein at least one carbon atom is substituted, wherein “x” is an integer from one to ten. The term “unsubstituted C₁-C_(x) alkylene” refers to alkylene groups having from one to x carbon atoms that are not substituted, wherein “x” is an integer from one to ten. The term “alkylene” as used herein, refers to a moiety with the formula —(CH₂)_(a)—, wherein “a” is an integer from one to ten.

The term “substituted C₂-C_(x) alkenyl” refers to alkenyl groups having from two to x carbon atoms, wherein at least one carbon atom is substituted, wherein “x” is an integer from two to ten. The term “unsubstituted C₂-C_(x) alkenyl” refers to alkenyl groups having from two to x carbon atoms that are not substituted, wherein “x” is an integer from two to ten.

The term “substituted C₂-C_(x) alkynyl” refers to alkynyl groups having from two to x carbon atoms, wherein at least one carbon atom is substituted, wherein “x” is an integer from two to ten. The term “unsubstituted C₂-C_(x) alkynyl” refers to alkynyl groups having from two to x carbon atoms that are not substituted, wherein “x” is an integer from two to ten.

The term “substituted C₁-C_(x) alkoxy” refers to alkoxy groups having from one to x carbon atoms, wherein at least one carbon atom is substituted, wherein “x” is an integer from one to ten. The term “unsubstituted C₁-C_(x) alkoxy” refers to alkoxy groups having from one to x carbon atoms that are not substituted, wherein “x” is an integer from one to ten.

The term “substituted C₁-C_(x) alkylamino” refers to alkylamino groups having from one to x carbon atoms, wherein at least one carbon atom is substituted, wherein “x” is an integer from one to ten. The term “unsubstituted C₁-C_(x) alkylamino” refers to alkyl groups having from one to x carbon atoms that are not substituted, wherein “x” is an integer from one to ten. The terms “alkylamine” and “alkylamino” are used interchangeably. In any alkylamino, where the nitrogen atom is substituted with one, two, or three substituents, the nitrogen atom can be referred to as a secondary, tertiary, or quaternary nitrogen atom, respectively.

The term “substituted alkylthio” refers to alkylthio groups having from one to x carbon atoms, wherein at least one carbon atom is substituted, wherein “x” is an integer from one to ten. The term “unsubstituted C₁-C_(x) alkylthio” refers to alkylthio groups having from one to x carbon atoms that are not substituted, wherein “x” is an integer from one to ten.

The term “substituted C₁-C_(x) carbonyl” refers to carbonyl groups having from one to x carbon atoms, wherein at least one carbon atom is substituted, wherein “x” is an integer from one to ten. The term “unsubstituted C₁-C_(x) carbonyl” refers to carbonyl groups having from one to x carbon atoms that are not substituted, wherein “x” is an integer from one to ten.

The term “substituted C₁-C_(x) carboxyl” refers to carboxyl groups having from one to x carbon atoms, wherein at least one carbon atom is substituted, wherein “x” is an integer from one to ten. The term “unsubstituted C₁-C_(x) carboxyl” refers to carboxyl groups having from one to x carbon atoms that are not substituted, wherein “x” is an integer from one to ten.

The term “substituted C₁-C_(x) amido” refers to amido groups having from one to x carbon atoms, wherein at least one carbon atom is substituted, wherein “x” is an integer from one to ten. The term “unsubstituted C₁-C_(x) amido” refers to amido groups having from one to x carbon atoms that are not substituted, wherein “x” is an integer from one to ten.

The term “substituted C₁-C_(x) sulfonyl” refers to sulfonyl groups having from one to x carbon atoms, wherein at least one carbon atom is substituted, wherein “x” is an integer from one to ten. The term “unsubstituted C₁-C_(x) sulfonyl” refers to sulfonyl groups having from one to x carbon atoms that are not substituted, wherein “x” is an integer from one to ten.

The term “substituted sulfonic acid” refers to sulfonic acid groups having from one to x carbon atoms, wherein at least one carbon atom is substituted, wherein “x” is an integer from one to ten. The term “unsubstituted C₁-C_(x) sulfonic acid” refers to sulfonic acid groups having from one to x carbon atoms that are not substituted, wherein “x” is an integer from one to ten.

The term “substituted C₁-C_(x) sulfamoyl” refers to sulfamoyl groups having from one to x carbon atoms, wherein at least one carbon atom is substituted, wherein “x” is an integer from one to ten. The term “unsubstituted C₁-C_(x) sulfamoyl” refers to sulfamoyl groups having from one to x carbon atoms that are not substituted, wherein “x” is an integer from one to ten.

The term “substituted C₁-C_(x) sulfoxide” refers to sulfoxide groups having from one to x carbon atoms, wherein at least one carbon atom is substituted, wherein “x” is an integer from one to ten. The term “unsubstituted C₁-C_(x) sulfoxide” refers to sulfoxide groups having from one to x carbon atoms that are not substituted, wherein “x” is an integer from one to ten.

The term “substituted C₁-C_(x) phosphoryl” refers to phosphoryl groups having from one to x carbon atoms, wherein at least one carbon atom is substituted, wherein “x” is an integer from one to ten. The term “unsubstituted C₁-C_(x) phosphoryl” refers to phosphoryl groups having from one to x carbon atoms that are not substituted, wherein “x” is an integer from one to ten.

The term “substituted C₁-C_(x) phosphonyl” refers to phosphonyl groups having from one to x carbon atoms, wherein at least one carbon atom is substituted, wherein “x” is an integer from one to ten. The term “unsubstituted C₁-C_(x) phosphonyl” refers to phosphonyl groups having from one to x carbon atoms that are not substituted, wherein “x” is an integer from one to ten.

The term “substituted C₀-C_(x) sulfonyl” refers to sulfonyl groups having from zero to x carbon atoms, wherein, if present, at least one carbon atom is substituted, wherein “x” is an integer from zero to ten. The term “unsubstituted C₀-C_(x) sulfonyl” refers to sulfonyl groups having from zero to x carbon atoms that are not substituted, wherein “x” is an integer from zero to ten.

The term “substituted C₀-C_(x) sulfonic acid” refers to sulfonic acid groups having from zero to x carbon atoms, wherein, if present, at least one carbon atom is substituted, wherein “x” is an integer from zero to ten. The term “unsubstituted C₀-C_(x) sulfonic acid” refers to sulfonic acid groups having from zero to x carbon atoms that are not substituted, wherein “x” is an integer from zero to ten.

The term “substituted C₀-C_(x) sulfamoyl” refers to sulfamoyl groups having from zero to x carbon atoms, wherein, if present, at least one carbon atom is substituted, wherein “x” is an integer from zero to ten. The term “unsubstituted C₀-C_(x) sulfamoyl” refers to sulfamoyl groups having from zero to x carbon atoms that are not substituted, wherein “x” is an integer from zero to ten.

The term “substituted C₀-C_(x) sulfoxide” refers to sulfoxide groups having from zero to x carbon atoms, wherein at least one carbon atom is substituted, wherein “x” is an integer from zero to ten. The term “unsubstituted C₀-C_(x) sulfoxide” refers to sulfoxide groups having from zero to x carbon atoms that are not substituted, wherein “x” is an integer from zero to ten.

The term “substituted C₀-C_(x) phosphoryl” refers to phosphoryl groups having from zero to x carbon atoms, wherein, if present, at least one carbon atom is substituted, wherein “x” is an integer from zero to ten. The term “unsubstituted C₀-C_(x) phosphoryl” refers to phosphoryl groups having from zero to x carbon atoms that are not substituted, wherein “x” is an integer from zero to ten.

The term “substituted C₀-C_(x) phosphonyl” refers to phosphonyl groups having from zero to x carbon atoms, wherein, if present, at least one carbon atom is substituted, wherein “x” is an integer from zero to ten. The term “unsubstituted C₀-C_(x) phosphonyl” refers to phosphonyl groups having from zero to x carbon atoms that are not substituted, wherein “x” is an integer from zero to ten.

The terms substituted “C_(x) alkyl,” “C_(x) alkylene,” “C_(x) alkenyl,” “C_(x) alkynyl,” “C_(x) alkoxy,” “C_(x) alkylamino,” “C_(x) alkylthio,” “C_(x) carbonyl,” “C_(x) carboxyl,” “C_(x) amido,” “C_(x) sulfonyl,” “C_(x) sulfonic acid,” “C_(x) sulfamoyl,” “C_(x) phosphoryl,” and “C_(x) phosphonyl” refer to alkyl, alkylene, alkenyl, alkynyl, alkoxy, alkylamino, alkylthio, carbonyl, carboxyl, amido, sulfonyl, sulfonic acid, sulfamoyl, sulfoxide, phosphoryl, and phosphonyl groups, respectively, having x carbon atoms, wherein at least one carbon atom is substituted, wherein “x” is an integer from one to ten. The terms unsubstituted “C_(x) alkyl,” “C_(x) alkylene,” “C_(x) alkenyl,” “C_(x) alkynyl,” “C_(x) alkoxy,” “C_(x) alkylamino”, “C_(x) alkylthio,” “C_(x) carbonyl,” “C_(x) carboxyl,” “C_(x) amido,” “C_(x) sulfonyl,” “C_(x) sulfonic acid,” “C_(x) sulfamoyl,” “C_(x) phosphoryl,” and “C_(x) phosphonyl” refer to alkyl, alkylene, alkenyl, alkynyl, alkoxy, alkylamino, alkylthio, carbonyl, carboxyl, amido, sulfonyl, sulfonic acid, sulfamoyl, sulfoxide, phosphoryl, and phosphonyl groups, respectively, having x carbon atoms that are not substituted, wherein “x” is an integer from one to ten.

II. Continuous Glucose Monitors (CGMs)

CGMs containing a sensor electrode, whose surface has been partially or completely coated with one or more layers of a material containing a zwitterionic polymer, are described. CGMs containing a surface-modified sensor electrode possess improved properties, e.g., reduced discordance between an actual physical measurement and a signal generated by the CGM to indicate levels of the actual physical measurement, when the sensor electrode is in contact with a bodily fluid, as compared a corresponding CGM having a sensor electrode that lacks the zwitterionic polymer on its surface. In the case of CGMs, the actual physical measurement can be the level of glucose in the blood of a subject, which can be determined via a method such as a finger-prick glucose strip measurement. In particular, CGMs with a coated sensor electrode eliminate and/or show reduced discordance between blood glucose levels and sensor signals after just one initial calibration using blood glucose levels from a strip test, a significant improvement over current commercially available CGMs. Preferably, the zwitterionic polymer contains methacryloyloxyethyl phosphocholine, 2-(6,8-dimercaptooctanamido)ethyl methacrylate, 2-(5-(1,2-dithiolan-3-yl)pentanamido)ethyl methacrylate monomeric units, or a combination thereof. Most preferably, the zwitterionic polymer contains methacryloyloxyethyl phosphocholine and 2-(6,8-dimercaptooctanamido)ethyl methacrylate monomeric units.

A. Zwitterionic Polymers

The polymers used to coat the sensor electrode of the CGMs contain a backbone and a plurality of side chains formed by monomer subunit A, and optionally monomer subunits B, C, or both. Each A within the polymer is a zwitterionic monomer. The A subunits can be formed from monomers having the same zwitterion or from monomers having different zwitterions. Each B is independently a monomer with a reactive side chain. The B subunits can be formed from monomers having the same reactive side chain or from monomers having different reactive side chains. Each C is independently a hydrophobic monomer or a neutral hydrophilic monomer. The C subunits can be formed from the monomers with having the same hydrophobic or neutral side chain or from monomers having different hydrophobic or neutral side chains.

In some forms, the zwitterionic polymers can be mixed or blended with other non-zwitterionic polymers to form a mixture. The non-zwitterionic polymers can be hydrophilic, hydrophobic, or amphiphilic.

The zwitterionic polymers can be biocompatible, biodegradable, non-biodegradable, or a combination thereof. The polymers can be purified after synthesis to remove any unreacted or partially reacted contaminants present with the chemically polymeric product.

1. Polymer Backbone

The polymer backbone can be neutral (e.g., polyalkylene or polyether) or contain permanently charged moieties (e.g., cyclic or acyclic quaternized nitrogen atoms), or even zwitterionic backbones (e.g., phosphorylcholine backbones). Therefore, the backbone of the polymers can be formed from polymers that include, but are not limited to, poly(acrylate), poly(methacrylate), poly(acrylamide), poly(methacrylamide), poly(vinyl alcohol), poly(ethylene vinyl acetate), poly(vinyl acetate), polyolefin, polyester, polyanhydride, poly (orthoester), polyamide, polyamine, polyether, polyazine, poly(carbonate), polyetheretherketone (PEEK), polyguanidine, polyimide, polyketal, poly(ketone), polyphosphazine, polysaccharide, polysiloxane, polysulfone, polyurea, polyurethane, combinations thereof.

2. Monomers Used to Form the Polymers

i. Zwitterionic Monomers

Each zwitterionic monomer within the polymer is denoted A. The zwitterionic monomers contain carboxybetaine moieties, sulfobetaine moieties, and phosphoryl choline moieties.

The zwitterionic moieties can be represented by:

wherein d is the point of covalent attachment of the zwitterion to the backbone of the polymer.

In some forms, Z can be a carboxylate, phosphate, phosphonic, phosphonate, sulfate, sulfinic, or sulfonate. The zwitterionic monomers can be provided in their zwitterionic states, as precursor monomers containing a protecting group, or combinations thereof. After the polymerization reaction, the precursor monomers can be deprotected to produce the zwitterionic monomer. For example, the precursor to a carboxybetaine monomer can be a cationic carboxybetaine ester. After polymerization the cationic carboxybetaine ester is hydrolyzed thereby converting it to the carboxybetaine, i.e., zwitterion.

In some forms, R₆-R₁₈ are independently unsubstituted alkyl, substituted alkyl, unsubstituted alkenyl, substituted alkylene, unsubstituted alkylene, substituted alkenyl, unsubstituted alkynyl, substituted alkynyl, unsubstituted aryl, substituted aryl, unsubstituted heteroaryl, substituted heteroaryl, unsubstituted alkoxy, substituted alkoxy, unsubstituted aroxy, substituted aroxy, unsubstituted alkylthio, substituted alkylthio, unsubstituted arylthio, substituted arylthio, unsubstituted carbonyl, substituted carbonyl, unsubstituted carboxyl, substituted carboxyl, unsubstituted amino, substituted amino, unsubstituted amido, substituted amido, unsubstituted sulfonyl, substituted sulfonyl, unsubstituted sulfamoyl, substituted sulfamoyl, unsubstituted phosphonyl, substituted phosphonyl, unsubstituted polyaryl, substituted polyaryl, unsubstituted C₃-C₂₀ cyclic, substituted C₃-C₂₀ cyclic, unsubstituted C₃-C₂₀ heterocyclic, substituted C₃-C₂₀ heterocyclic, amino acid, poly(ethylene glycol), poly(lactic-co-glycolic acid), peptide, or polypeptide group.

In some forms, R₆-R₁₈ are independently unsubstituted C₁-C₁₀ alkyl, substituted C₁-C₁₀ alkyl, unsubstituted C₁-C₁₀ alkenyl, substituted C₁-C₁₀ alkylene, unsubstituted C₁-C₁₀ alkylene, substituted C₁-C₁₀ alkenyl, unsubstituted C₁-C₁₀ alkynyl, substituted C₁-C₁₀ alkynyl, unsubstituted aryl, substituted aryl, unsubstituted heteroaryl, substituted heteroaryl, unsubstituted C₁-C₁₀ alkoxy, substituted C₁-C₁₀ alkoxy, unsubstituted aroxy, substituted aroxy, unsubstituted C₁-C₁₀ alkylthio, substituted C₁-C₁₀ alkylthio, unsubstituted arylthio, substituted arylthio, unsubstituted C₁-C₁₀ carbonyl, substituted C₁-C₁₀ carbonyl, unsubstituted C₁-C₁₀ carboxyl, substituted C₁-C₁₀ carboxyl, unsubstituted C₁-C₁₀ amino, substituted C₁-C₁₀ amino, unsubstituted C₁-C₁₀ amido, substituted C₁-C₁₀ amido, unsubstituted C₁-C₁₀ sulfonyl, substituted C₁-C₁₀ sulfonyl, unsubstituted C₁-C₁₀ sulfamoyl, substituted C₁-C₁₀ sulfamoyl, unsubstituted C₁-C₁₀ phosphonyl, substituted C₁-C₁₀ phosphonyl, unsubstituted polyaryl, substituted polyaryl, unsubstituted C₃-C₂₀ cyclic, substituted C₃-C₂₀ cyclic, unsubstituted C₃-C₂₀ heterocyclic, or substituted C₃-C₂₀ heterocyclic.

In some forms, R₆-R₁₈ are unsubstituted C₁-C₅ alkyl, substituted C₁-C₅ alkyl, unsubstituted C₁-C₅ alkenyl, substituted C₁-C₅ alkylene, unsubstituted C₁-C₅ alkylene, substituted C₁-C₅ alkenyl, unsubstituted C₁-C₅ alkynyl, substituted C₁-C₅ alkynyl, unsubstituted aryl, substituted aryl, unsubstituted heteroaryl, substituted heteroaryl, unsubstituted C₁-C₅ alkoxy, substituted C₁-C₅ alkoxy, unsubstituted aroxy, substituted aroxy, unsubstituted C₁-C₅ alkylthio, substituted C₁-C₅ alkylthio, unsubstituted arylthio, substituted arylthio, unsubstituted C₁-C₅ carbonyl, substituted C₁-C₅ carbonyl, unsubstituted C₁-C₅ carboxyl, substituted C₁-C₅ carboxyl, unsubstituted C₁-C₅ amino, substituted C₁-C₅ amino, unsubstituted C₁-C₅ amido, substituted C₁-C₅ amido, unsubstituted C₁-C₅ sulfonyl, substituted C₁-C₅ sulfonyl, unsubstituted C₁-C₅ sulfamoyl, substituted C₁-C₅ sulfamoyl, unsubstituted C₁-C₅ phosphonyl, substituted C₁-C₅ phosphonyl, unsubstituted polyaryl, substituted polyaryl, unsubstituted C₃-C₁₀ cyclic, substituted C₃-C₁₀ cyclic, unsubstituted C₃-C₁₀ heterocyclic, or substituted C₃-C₂₀ heterocyclic.

In some forms, R₆, R₉, R₁₀, R₁₁ and R₁₅, are independently unsubstituted C₁-C₅ alkyl, substituted C₁-C₅ alkyl, substituted C₁-C₅ alkylene, or unsubstituted C₁-C₅ alkylene, C₁-C₅ alkoxy, substituted C₁-C₅ alkoxy, unsubstituted aroxy, substituted aroxy, unsubstituted C₁-C₅ alkylthio, substituted C₁-C₅ alkylthio, unsubstituted arylthio, substituted arylthio, unsubstituted C₁-C₅ carbonyl, substituted C₁-C₅ carbonyl, unsubstituted C₁-C₅ carboxyl, substituted C₁-C₅ carboxyl, unsubstituted C₁-C₅ amino, substituted C₁-C₅ amino, unsubstituted C₁-C₅ amido, substituted C₁-C₅ amido, unsubstituted C₁-C₅ sulfonyl, substituted C₁-C₅ sulfonyl, unsubstituted C₁-C₅ sulfamoyl, substituted C₁-C₅ sulfamoyl, unsubstituted C₁-C₅ phosphonyl, or substituted C₁-C₅ phosphonyl.

In some forms, R₇, R₈, R₁₂, R₁₃, R₁₄, R₁₆, R₁₇, and R₁₈, are independently hydrogen, unsubstituted C₁-C₅ alkyl, or substituted C₁-C₅ alkyl.

In some forms, the zwitterionic moieties can be:

or combinations thereof.

ii. Monomers with a Reactive Side Chain

The zwitterionic polymers optionally contain a monomer, B, with a reactive site chain. The reactive side chain can be represented by the formula:

d-R₁—Y,   Formula IV

d is the point of covalent attachment of the reactive side chain to the backbone of the polymer.

In some forms, R₁ is alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, alkoxy, substituted alkoxy, aroxy, substituted aroxy, alkylthio, substituted alkylthio, arylthio, substituted arylthio, carbonyl, substituted carbonyl, carboxyl, substituted carboxyl, amino, substituted amino, amido, substituted amido, sulfonyl, substituted sulfonyl, sulfamoyl, substituted sulfamoyl, phosphonyl, substituted phosphonyl, polyaryl, substituted polyaryl, C₃-C₂₀ cyclic, substituted C₃-C₂₀ cyclic, heterocyclic, substituted heterocyclic, amino acid, poly(ethylene glycol), poly(lactic-co-glycolic acid), peptide, or polypeptide group.

In some forms, R₁ is -Aq-unsubstituted C₁-C₁₀ alkylene-Bq-unsubstituted C₁-C₁₀ alkylene-, Aq-unsubstituted C₁-C₁₀ alkylene-Bq-substituted C₁-C₁₀ alkylene-, -Aq-substituted C₁-C₁₀ alkylene-Bq-unsubstituted C₁-C₁₀ alkylene-, or Aq-substituted C₁-C₁₀ alkylene-Bq-substituted C₁-C₁₀ alkylene-, wherein Aq and Bq are independently —C(O)O—, —C(O)NH—, —OC(O)—, —NHC(O)—, —O—, —NH—NHC(O)—, —OC(O)NH—, —NHC(O)O—, —C(O)—, —OC(O)O—, —S(═O₂)₂—, —S(═O)—, —S—, —N═N—, or —N═CH—.

In some forms, R₁ is -Aq-unsubstituted C₁-C₅ alkylene-Bq-unsubstituted C₁-C₅ alkylene-, Aq-unsubstituted C₁-C₅ alkylene-Bq-substituted C₁-C₅ alkylene-, -Aq-substituted C₁-C₅ alkylene-Bq-unsubstituted C₁-C₅ alkylene-, or Aq-substituted C₁-C₅ alkylene-Bq-substituted C₁-C₅ alkylene-, wherein Aq and Bq are independently —C(O)O—, —C(O)NH—, —OC(O)—, —NHC(O)——O—, —NH—NHC(O)—, —OC(O)NH—, —NHC(O)O—, —C(O)—, —OC(O)O—, —S(═O₂)₂—, —S(═O)—, —S—, —N═N—, or —N═CH—.

In some forms, R₁ is —C(O)O-unsubstituted C₂ alkylene-NHC(O)-unsubstituted C₄ alkylene-, —C(O)O-unsubstituted C₂ alkylene-NHC(O)-substituted C₄ alkylene-, —C(O)O-substituted C₂ alkylene-NHC(O)-unsubstituted C₄ alkylene-, or —C(O)O-substituted C₂ alkylene-NHC(O)-substituted C₄ alkylene-.

In some forms, Y is propane-1,3-dithiol, 1,2-dithiolan-3-yl, 1,2-dithiol-3-ylidene, amine, hydrogen, —SH, maleimide, aziridine, —N₃, —CN, acryloyl, acrylamide, —C(O)OR₂, —C(O)R₃, vinyl sulfone, —OH, cyanate, thiocyanate, isocyanate, isothiocyanate, alkoxysilane, vinyl silane, silicon hydride, —NR₄R₅, acetohydrazide, acyl azide, acyl halides, N-hydroxysuccinimide ester, sulfonyl chloride, glyoxal, epoxide, carbodiimides, aryl halides, imido ester.

In some forms, R₁ is alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, alkoxy, aroxy, substituted aroxy, alkylthio, substituted alkylthio, arylthio, substituted arylthio, carbonyl, carboxyl, amido, sulfonyl, substituted sulfonyl, sulfamoyl, substituted sulfamoyl, phosphonyl, substituted phosphonyl, polyaryl, substituted polyaryl, C₃-C₂₀ cyclic, substituted C₃-C₂₀ cyclic, heterocyclic, substituted heterocyclic, amino acid, poly(lactic-co-glycolic acid), peptide, or polypeptide group; and Y is propane-1,3-dithiol, 1,2-dithiolan-3-yl, 1,2-dithiol-3-ylidene, hydrogen, —SH, maleimide, aziridine, —N₃, —CN, acryloyl, acrylamide, —C(O)OR₂, —C(O)R₃, vinyl sulfone, —OH, cyanate, thiocyanate, isocyanate, isothiocyanate, alkoxysilane, vinyl silane, silicon hydride, —NR₄R₅, acetohydrazide, acyl azide, acyl halides, N-hydroxysuccinimide ester, sulfonyl chloride, glyoxal, epoxide, carbodiimides, aryl halides, imido ester, or

R₁ is alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, alkoxy, substituted alkoxy, aroxy, substituted aroxy, alkylthio, substituted alkylthio, arylthio, substituted arylthio, carbonyl, substituted carbonyl, carboxyl, substituted carboxyl, amino, substituted amino, amido, substituted amido, sulfonyl, substituted sulfonyl, sulfamoyl, substituted sulfamoyl, phosphonyl, substituted phosphonyl, polyaryl, substituted polyaryl, C₃-C₂₀ cyclic, substituted C₃-C₂₀ cyclic, heterocyclic, substituted heterocyclic, amino acid, poly(ethylene glycol), poly(lactic-co-glycolic acid), peptide, or polypeptide group; and Y is propane-1,3-dithiol, 1,2-dithiolan-3-yl, 1,2-dithiol-3-ylidene, —SH, maleimide, aziridine, —N₃, —CN, acrylamide, —C(O)OR₂, —C(O)R₃, vinyl sulfone, cyanate, thiocyanate, isocyanate, isothiocyanate, vinyl silane, silicon hydride, acetohydrazide, acyl azide, acyl halides, N-hydroxysuccinimide ester, sulfonyl chloride, glyoxal, carbodiimides, aryl halides, imido ester.

In some forms, R₂, R₄, and R₅, are, independently, hydrogen, amino, hydroxyl, thiol, oxo, phosphate, or substituted or unsubstituted C₁-C₁₀ alkyl, C₁-C₁₀ alkylene, C₂-C₁₀ alkenyl, C₂-C₁₀ alkynyl, C₁-C₁₀ alkoxy, C₁-C₁₀ alkylamino, C₁-C₁₀ alkylthio, aryl, substituted aryl, heteroaryl, substituted heteroaryl, alkoxy, substituted alkoxy, aroxy, substituted aroxy, alkylthio, substituted alkylthio, arylthio, substituted arylthio, carbonyl, substituted carbonyl, carboxyl, substituted carboxyl, amino, substituted amino, amido, substituted amido, polyaryl, substituted polyaryl, C₃-C₂₀ cyclic, substituted C₃-C₂₀ cyclic, heterocyclic, or substituted heterocyclic; and wherein R₃ is hydrogen, amino, hydroxyl, thiol, oxo, phosphate, or substituted or unsubstituted C₁-C₁₀ alkyl, C₁-C₁₀ alkylene, C₂-C₁₀ alkenyl, C₂-C₁₀ alkynyl, C₁-C₁₀ alkoxy, C₁-C₁₀ alkylamino, C₁-C₁₀ alkylthio, aryl, substituted aryl, heteroaryl, substituted heteroaryl, alkoxy, substituted alkoxy, aroxy, substituted aroxy, alkylthio, substituted alkylthio, arylthio, substituted arylthio, carbonyl, substituted carbonyl, carboxyl, substituted carboxyl, amino, substituted amino, amido, substituted amido, polyaryl, substituted polyaryl, C₃-C₂₀ cyclic, substituted C₃-C₂₀ cyclic, heterocyclic, or substituted heterocyclic.

iii. Hydrophobic Monomer

The polymers optionally contain a hydrophobic monomer with a hydrophobic side chain, represented by:

d is the point of covalent attachment of the hydrophobic side chain to the backbone of the polymer.

In some forms, R₁₉ and R₂₀ are independently unsubstituted alkyl, substituted alkyl, unsubstituted alkenyl, substituted alkenyl, unsubstituted alkynyl, substituted alkynyl, unsubstituted aryl, substituted aryl, unsubstituted heteroaryl, substituted heteroaryl, unsubstituted alkoxy, substituted alkoxy, unsubstituted aroxy, substituted aroxy, unsubstituted alkylthio, substituted alkylthio, unsubstituted arylthio, substituted arylthio, unsubstituted carbonyl, substituted carbonyl, unsubstituted carboxyl, substituted carboxyl, unsubstituted amino, substituted amino, unsubstituted amido, substituted amido, unsubstituted sulfonyl, substituted sulfonyl, unsubstituted sulfamoyl, substituted sulfamoyl, unsubstituted phosphonyl, substituted phosphonyl, —O—, —S—, —NH—NHC(O)—, —N═N—, —N═CH—, unsubstituted polyaryl, substituted polyaryl, unsubstituted C₃-C₂₀ cyclic, substituted C₃-C₂₀ cyclic, unsubstituted C₃-C₂₀ heterocyclic, substituted C₃-C₂₀ heterocyclic, amino acid, poly(ethylene glycol), poly(lactic-co-glycolic acid), peptide, or polypeptide group.

In some forms, R₁₉ is —C(O)NH—, —C(O)O—, —NHC(O)—, —OC(O)—, —O—, —NH—NHC(O)—, —OC(O)NH—, —NHC(O)O—, —C(O)—, —OC(O)O—, —S(═O₂)₂—, —S(═O)—, —S—, —N═N—, or —N═CH—.

In some forms, R₂₀ has the structure:

-Az-Bz-(-Cz)δ,   Formula VII

wherein δ is an integer between 0 and 10, inclusive, preferably δ is 1.

In some forms of Formula VII, Az can be:

wherein R₃₁ in Az is —(CR₃₂R₃₂)_(p)—; p is an integer from 0 to 5; each R₃₂ is hydrogen, unsubstituted alkyl, or substituted alkyl; each R^(e) is independently unsubstituted alkyl, substituted alkyl, unsubstituted alkenyl, unsubstituted alkenyl, unsubstituted alkynyl, substituted alkynyl, unsubstituted alkoxy, substituted alkoxy, unsubstituted alkylamino, substituted alkylamino, unsubstituted dialkylamino, substituted dialkylamino, hydroxy, unsubstituted aryl, substituted aryl, unsubstituted heteroaryl, substituted heteroaryl, unsubstituted carboxyl, substituted carboxyl, unsubstituted amino, substituted amino, unsubstituted amido, substituted amido, unsubstituted C₃-C₂₀ cyclic, substituted C₃-C₂₀ cyclic, unsubstituted C₃-C₂₀ heterocyclic, or substituted C₃-C₂₀ heterocyclic; y is an integer between 0 and 11, inclusive; R₂₅, R₂₆, R₂₇, R₂₈, R₂₉, and R₃₀ are independently C or N, wherein the bonds between adjacent R₂₅ to R₃₀ are double or single according to valency, and wherein R₂₅ to R₃₀ are bound to none, one, or two hydrogens according to valency.

In some forms of Formula VIII, each R₃₂ is hydrogen, and p is 1.

In some forms of Formula VIII, each R₃₂ is hydrogen, p is 1, R₂₅ is C, and R₂₆-R₃₀ are CH, and the bonds between R₂₅ and R₂₆, between R₂₇ and R₂₈, and between R₂₉ and R₃₀ are double bonds.

In some forms of Formula VIII, each R₃₂ is hydrogen, p is 1, R₂₅ is C, and R₂₆-R₃₀ are CH, and the bonds between R₂₅ and R₂₆, between R₂₇ and R₂₈, and between R₂₀ and R₃₀ are double bonds, and y is 1.

In some forms of Formula VIII, each R₃₂ is hydrogen, p is 1, R₂₅ is C, and R₂₆-R₃₀ are CH, and the bonds between R₂₅ and R₂₆, between R₂₇ and R₂₈, and between R₂₀ and R₃₀ are double bonds, y is 1, and R^(e) is Bz.

In some forms of Formula VIII, each R₃₂ is hydrogen, p is 1, R₂₅ is C, and R₂₆-R₃₀ are CH, and the bonds between R₂₅ and R₂₆, between R₂₇ and R₂₈, and between R₂₀ and R₃₀ are double bonds, y is 1, and R^(e) contains a substituted heteroaryl group.

In some forms of Formula VIII, each R₃₂ is hydrogen, p is 1, R₂₅ is C, and R₂₆-R₃₀ are CH, and the bonds between R₂₅ and R₂₆, between R₂₇ and R₂₈, and between R₂₀ and R₃₀ are double bonds, y is 1, R^(e) contains a substituted heteroaryl group, wherein the substituted heteroaryl group is a substituted triazole.

In some forms of Formula VII, Az can be:

wherein R₃₂, R₃₃, R₃₄, R₃₅, R₃₆, R₃₇, R₃₈, and R₃₀ in Az are independently hydrogen, unsubstituted alkyl, substituted alkyl, unsubstituted alkenyl, substituted alkenyl, unsubstituted alkynyl, substituted alkynyl, unsubstituted phenyl, substituted phenyl, unsubstituted aryl, substituted aryl, unsubstituted heteroaryl, substituted heteroaryl, unsubstituted arylalkyl, substituted arylalkyl, unsubstituted alkoxy, substituted alkoxy, unsubstituted aroxy, substituted aroxy, unsubstituted carbonyl, substituted carbonyl, unsubstituted carboxyl, substituted carboxyl, unsubstituted amino, substituted amino, unsubstituted amido, substituted amido, unsubstituted C₃-C₂₀ cyclic, substituted C₃-C₂₀ cyclic, unsubstituted C₃-C₂₀ heterocyclic, substituted C₃-C₂₀ heterocyclic, poly(ethylene glycol), or poly(lactic-co-glycolic acid); k is an integer from 0 to 20; each X_(d) is independently absent, 0, or S; and R^(c) can be Bz.

In some forms of Formula IX, X_(d) is O. In some forms of Formula IX, X_(d) is O, and R₃₂-R₃₉ are hydrogen.

In some forms of Formula IX, X_(d) is O, R₃₂-R₃₀ are hydrogen, and k is an integer between 1 and 5, inclusive, preferably 3.

In some forms of Formula VII or IX, Bz can be:

wherein R₄₅ in Bz is —(CR₄₆R₄₆)_(p)—; p is an integer from 0 to 5; each R₄₆ is hydrogen, unsubstituted alkyl, or substituted alkyl; each R^(d) is independently unsubstituted alkyl, substituted alkyl, unsubstituted alkenyl, unsubstituted alkenyl, unsubstituted alkynyl, substituted alkynyl, unsubstituted alkoxy, substituted alkoxy, unsubstituted alkylamino, substituted alkylamino, unsubstituted dialkylamino, substituted dialkylamino, hydroxy, unsubstituted aryl, substituted aryl, unsubstituted heteroaryl, substituted heteroaryl, unsubstituted carboxyl, substituted carboxyl, unsubstituted amino, substituted amino, unsubstituted amido, substituted amido, unsubstituted C₃-C₂₀ cyclic, substituted C₃-C₂₀ cyclic, unsubstituted C₃-C₂₀ heterocyclic, or substituted C₃-C₂₀ heterocyclic; w is an integer between 0 and 4, inclusive; each R₄₀, R₄₁, R₄₂, R₄₃, and R₄₄, are independently C or N, wherein the bonds between adjacent R₄₀ to R₄₄ are double or single according to valency, and wherein R₄₀ to R₄₄ are bound to none, one, or two hydrogens according to valency.

In some forms of Formula X, p is 0.

In some forms of Formula X, p is 0, and R₄₀-R₄₂ are N.

In some forms of Formula X, p is 0, R₄₀-R₄₂ are N, and R₄₃ and R₄₄ are C.

In some forms, Formula X is:

wherein R₄₈ and R₄₉ are independently hydrogen,

with the proviso that at least one of R₄₈ and R₄₉ is not hydrogen.

In some forms of Formula VII or Formula XI, Cz can be:

wherein R₃₁ in Cz is —(CR₃₂R₃₂)_(p)— or —(CR₃₂R₃₂)_(p)—X_(b)—(CR₃₂R₃₂)_(q)—; p and q are independently integers between 0 to 5, inclusive; each R₃₂ is hydrogen, unsubstituted alkyl, or substituted alkyl; X_(b) is absent, —O—, —S—, —S(O)—, —S(O)₂—, or NR₄₇; R₄₇ is unsubstituted alkyl or substituted alkyl; each R^(e) is independently unsubstituted alkyl, substituted alkyl, unsubstituted alkenyl, unsubstituted alkenyl, unsubstituted alkynyl, substituted alkynyl, unsubstituted alkoxy, substituted alkoxy, unsubstituted alkylamino, substituted alkylamino, unsubstituted dialkylamino, substituted dialkylamino, hydroxy, unsubstituted aryl, substituted aryl, unsubstituted heteroaryl, substituted heteroaryl, unsubstituted carboxyl, substituted carboxyl, unsubstituted amino, substituted amino, unsubstituted amido, substituted amido, unsubstituted C₃-C₂₀ cyclic, substituted C₃-C₂₀ cyclic, unsubstituted C₃-C₂₀ heterocyclic, or substituted C₃-C₂₀ heterocyclic; y is an integer between 0 and 11, inclusive; R₂₅, R₂₆, R₂₇, R₂₈, R₂₉, and R₃₀ are independently C or N, wherein the bonds between adjacent R₂₅ to R₃₀ are double or single according to valency, and wherein R₂₅ to R₃₀ are bound to none, one, or two hydrogens according to valency.

In some forms of Formula VIII, R₃₁ is —(CR₃₂R₃₂)_(p)—, each R₃₂ is hydrogen, and p is 1.

In some forms of Formula VIII, R₃₁ is —(CR₃₂R₃₂)_(p)—, each R₃₂ is hydrogen, p is 1, and R₂₅ is N.

In some forms of Formula VIII, R₃₁ is —(CR₃₂R₃₂)_(p)—, each R₃₂ is hydrogen, p is 1, R₂₅ is N, and R₂₈ is S(O)₂.

In some forms of Formula VIII, R₃₁ is —(CR₃₂R₃₂)_(p)—, each R₃₂ is hydrogen, p is 1, R₂₅ is N, R₂₈ is S(O)₂, and R₂₆, R₂₇, R₂₉, and R₃₀ are CH₂.

In some forms of Formula VIII, R₃₁ is —(CR₃₂R₃₂)_(p)—, each R₃₂ is hydrogen, p is 1, R₂₅ is N, R₂₈ is S(O)₂, R₂₆, R₂₇, R₂₉, and R₃₀ are CH₂, and y is 0, i.e.,

In some forms of Formula VIII, R₃₁ is —(CR₃₂R₃₂)_(p)—X_(b)—(CR₃₂R₃₂)_(q)—, each R₃₂ is hydrogen, and p is 0.

In some forms of Formula VIII, R₃₁ is —(CR₃₂R₃₂)_(p)—X_(b)—(CR₃₂R₃₂)_(q)—, each R₃₂ is hydrogen, p is 0, and q is 1.

In some forms of Formula VIII, R₃₁ is —(CR₃₂R₃₂)_(p)—X_(b)—(CR₃₂R₃₂)_(q)—, each R₃₂ is hydrogen, p is 0, q is 1, and X_(b) is O or —S(O)₂—.

In some forms of Formula VIII, R₃₁ is —(CR₃₂R₃₂)_(p)—X_(b)—(CR₃₂R₃₂)_(q)—, each R₃₂ is hydrogen, p is 0, q is 1, X_(b) is O, and R₂₆ is O.

In some forms of Formula VIII, R₃₁ is —(CR₃₂R₃₂)_(p)—X_(b)—(CR₃₂R₃₂)_(q)—, each R₃₂ is hydrogen, p is 0, q is 1, X_(b) is O, R₂₆ is O, and R₂₅ is CH.

In some forms of Formula VIII, R₃₁ is —(CR₃₂R₃₂)_(p)—X_(b)—(CR₃₂R₃₂)_(q)—, each R₃₂ is hydrogen, p is 0, q is 1, X_(b) is O, R₂₆ is O, R₂₅ is CH, R₂₇-R₃₀ are CH₂, and y is 0, i.e.,

In some forms of Formula VIII, R₃₁ is —(CR₃₂R₃₂)_(p)—X_(b)—(CR₃₂R₃₂)_(q)—, each R₃₂ is hydrogen, p is 0, q is 1, X_(b) is —S(O)₂—, R₂₅ is C, R₂₆-R₃₀ are CH, and the bonds between R₂₅ and R₂₆, between R₂₇ and R₂₈, and between R₂₉ and R₃₀ are double bonds, i.e.,

In some forms of Formula VIII, R₃₁ is —(CR₃₂R₃₂)_(p)—, and p is 0.

In some forms of Formula VIII, R₃₁ is —(CR₃₂R₃₂)_(p)—, p is 0, R₂₅ is C, and R₂₆-R₃₀ are CH, and the bonds between R₂₅ and R₂₆, between R₂₇ and R₂₈, and between R₂₀ and R₃₀ are double bonds.

In some forms of Formula VIII, R₃₁ is —(CR₃₂R₃₂)_(p)—, p is 0, R₂₅ is C, and R₂₆-R₃₀ are CH, the bonds between R₂₅ and R₂₆, between R₂₇ and R₂₈, and between R₂₀ and R₃₀ are double bonds, and y is 0 or 1.

In some forms of Formula VIII, R₃₁ is —(CR₃₂R₃₂)_(p)—, p is 0, R₂₅ is C, and R₂₆-R₃₀ are CH, the bonds between R₂₅ and R₂₆, between R₂₇ and R₂₈, and between R₂₀ and R₃₀ are double bonds, y is 1, and R^(e) is —NH₂, —OCH₃, or —CH₂OH, i.e.,

respectively.

In some forms of Formula VIII, R₃₁ is —(CR₃₂R₃₂)_(p)—, p is 0, R₂₅ is C, R₂₇ is N, R₂₆, R₂₈-R₃₀ are CH, the bonds between R₂₅ and R₂₆, between R₂₇ and R₂₈, and between R₂₀ and R₃₀ are double bonds, and y is 0, i.e.,

In some forms of Formula VIII, R₃₁ is —(CR₃₂R₃₂)_(p)—, p is 0, R₂₅ is C(OH), and R₂₆-R₃₀ are CH₂, and y is 0, i.e.,

In some forms, the hydrophobic monomeric unit contains the moiety:

-   -   or         combinations thereof.

iv. Neutral Hydrophilic Monomer

The polymers optionally contain a neutral hydrophilic monomer with a hydrophilic side chain represented by:

d is the point of covalent attachment of the neutral hydrophilic side chain to the backbone of the polymer.

p is an integer between 1 and 10,000, inclusive, preferably between 1 and 30, inclusive.

In some forms, R₂₁ is unsubstituted alkyl, substituted alkyl, unsubstituted alkenyl, substituted alkenyl, unsubstituted alkynyl, substituted alkynyl, unsubstituted aryl, substituted aryl, unsubstituted heteroaryl, substituted heteroaryl, unsubstituted alkoxy, substituted alkoxy, unsubstituted aroxy, substituted aroxy, unsubstituted alkylthio, substituted alkylthio, unsubstituted arylthio, substituted arylthio, unsubstituted carbonyl, substituted carbonyl, unsubstituted carboxyl, substituted carboxyl, unsubstituted amino, substituted amino, unsubstituted amido, substituted amido, unsubstituted sulfonyl, substituted sulfonyl, unsubstituted sulfamoyl, substituted sulfamoyl, unsubstituted phosphonyl, substituted phosphonyl, unsubstituted polyaryl, substituted polyaryl, unsubstituted C₃-C₂₀ cyclic, substituted C₃-C₂₀ cyclic, unsubstituted C₃-C₂₀ heterocyclic, substituted C₃-C₂₀ heterocyclic, amino acid, poly(ethylene glycol), poly(lactic-co-glycolic acid), peptide, or polypeptide group.

In some forms, R₂₂, R₂₃, and R₂₄ are independently hydrogen, alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, alkoxy, aroxy, substituted aroxy, alkylthio, substituted alkylthio, arylthio, substituted arylthio, carbonyl, carboxyl, amido, sulfonyl, substituted sulfonyl, sulfamoyl, substituted sulfamoyl, phosphonyl, substituted phosphonyl, polyaryl, substituted polyaryl, C₃-C₂₀ cyclic, substituted C₃-C₂₀ cyclic, heterocyclic, substituted heterocyclic, amino acid, poly(lactic-co-glycolic acid), peptide, or polypeptide group.

In some forms, R₂₁ is a substituted carbonyl, R₂₂, R₂₃, and R₂₄ are hydrogen, and p is an integer between 1 and 20, inclusive.

In some forms, R₂₁ is a substituted carbonyl, R₂₂ and R₂₃ are hydrogen, R₂₄ is methyl, and p is an integer between 1 and 1000, inclusive.

3. Weight Average Molecular Weight

The weight average molecular weight of the polymers can vary. In some forms, the weight average molecular weight of the polymer, as determined by size exclusion chromatography (SEC), can be between about 500 Daltons and about 50,000 Daltons, preferably between about 2,000 Daltons and about 30,000 Daltons, most preferably between about 5,000 Daltons and about 20,000 Daltons. The weight average molecular weights of the polymers can also depend on their degree of polymerization. In some forms, degree of polymerization is between about 2 and about 10,000, inclusive, between about 2 and about 5,000, inclusive, between about 5 and about 1,000, inclusive, between about 5 and about 500, inclusive, between about 10 and about 200, inclusive, or between about 20 and about 80, inclusive.

In some forms, the zwitterionic polymers are coated to a surface of the sensor electrode of a CGM. The zwitterionic polymer coatings can reduce discordance between actual blood glucose levels and signals generated by a CGM to indicate blood glucose levels, reduce the foreign body responses and fibrosis to the CGMs after implantation, compared to a corresponding CGM whose sensor electrode is not coated with the zwitterionic polymers described herein.

III. Methods of Making

A. Zwitterionic Polymers

Methods for the synthesis of the polymers from a zwitterionic monomer, monomer with a reactive side chain, and a monomer with a hydrophobic side chain or a monomer with a neutral hydrophilic side chain, are also provided. Any suitable method known in the art can be used to generate the polymers from monomers. In some forms, the monomers contain the zwitterionic side chains, reactive side chains, hydrophobic side chains and neutral hydrophilic side chains prior to polymerization. In some forms, the polymer is formed first, followed by modifications of the polymer to introduce the zwitterionic side chains, reactive side chains, hydrophobic side chains and neutral hydrophilic side chains. Exemplary zwitterionic polymers are shown in FIG. 1.

In some forms, the polymers are prepared via reversible addition-fragmentation chain transfer as shown in Scheme 1 and Scheme 2.

Scheme 1: Preparation of zwitterionic polymers containing two different zwitterionic monomers and a monomer with a reactive side chain. CTA—chain transfer agent; ACVA—4,4′-azobis(4-cyanovaleric acid); RAFT—Reversible addition-fragmentation chain transfer. M1—monomer with reactive side chain. Each x is independently an integer between 1 and 1,000, inclusive, preferably between 10 and 200, inclusive. Each y is independently an integer between 1 and 1,000, inclusive, preferably between 10 and 200, inclusive, most preferably between 10 and 20, inclusive. Each z is independently an integer between 1 and 1,000, inclusive, preferably between 10 and 200, inclusive. In this scheme the monomer feed ratio of MPC/M1/SB1 was 70:10:20.

In some forms, such as in Scheme 2 below, z can be zero. Accordingly, in some forms, x and y are independently integers between 1 and 1000, inclusive, preferably x is between 10 and 200, inclusive, preferably y is between 2 and 20, inclusive; and z is between 0 and 1000, inclusive, preferably z is between 10 and 200, inclusive.

Scheme 2: Preparation of zwitterionic polymers containing one kind of zwitterionic monomer and a monomer with a reactive side chain. CTA—chain transfer agent; ACVA—4,4′-azobis(4-cyanovaleric acid). x and y are independently integers between 1 and 1,000, inclusive, preferably x is between 10 and 200, inclusive, and preferably is between 2 and 20, inclusive. In some forms, step (i) can be performed in CTA/ACVA, methanol, and N,N-dimethyl acrylamide at 70° C.

The feed ratio of the monomer containing the reactive side chain to the zwitterionic monomer between about 1:1 and about 1:500, inclusive, between about 1:1 and about 1:100, inclusive, between about 1:1 and about 1:50, inclusive, between about 1:1 and about 1:30, inclusive, between about 1:1 and about 1:25, inclusive, or between about 1:1 and about 1:20, inclusive.

B. Coating the Sensor Electrode of a CGM with Zwitterionic Polymers

The zwitterionic polymers described herein can be coated onto the surfaces of CGMs, in particular the surface of the sensor electrode of CGMs. The zwitterionic polymers can be coated onto the sensor electrode of any CGM. The zwitterionic polymer coatings can reduce inflammatory responses to the CGMs post-implantation.

In some forms, the sensor electrode can be an enzyme-based sensor electrode. In general, sensor electrodes that contain an enzyme, such as the Medtronic CGM, include a shell (e.g. silicone shell) wrapped around an inner metal electrode. The inner electrode contains a conductive electrode (e.g. gold electrode) coated by a thin membrane layer embedded with a glucose specific enzyme (e.g. glucose oxidase (GO_(x)). The shell can be prepared from a variety of materials. In some forms, the material is biocompatible. Exemplary materials include silicone, metallic materials, metal oxides, polymeric materials, including degradable and non-degradable polymeric materials.

Many pharmaceutically acceptable polymers can be used to form the shell of the sensor electrodes onto which the polymeric zwitterions are coated. Exemplary polymers include, but are not limited to polyesters, polystyrene, polyurethane, polyphosphazenes, poly(acrylic acids), poly(methacrylic acids), poly(alkylene oxides), poly(vinyl acetate), polyvinylpyrrolidone (PVP), poly(vinyl amines), poly(vinyl pyridine), poly(vinyl imidazole), poly(anhydrides), poly(hydroxy acids), poly(ortho esters), poly(propylene fumarates), polyamides, polyamino acids, polyethers, polyacetals, polyhydroxyalkanoates, polyketals, polyesteramides, poly(dioxanones), polycarbonates, polyorthocarbonates, polycyanoacrylates, polyalkylene oxalates, polyalkylene succinates, poly(malic acid), poly(methyl vinyl ether), poly(ethylene imine), poly(maleic anhydride), copolymers and blends thereof.

The zwitterionic polymers can be covalently (directly or indirectly) or non-covalently associated with the surface of the sensor electrode. In some forms, the zwitterionic polymers are non-covalently associated with the surface. The zwitterionic polymers can be applied by any of a variety of techniques in the art including, but not limited to, spraying, wetting, immersing, dipping, such as dip coating, painting, or otherwise applying a hydrophobic, polycationic polymer to a surface of the implant.

In some forms, the zwitterionic polymers can be coated directly onto the surfaces of the biomaterials or devices. In some forms, the surfaces of the sensor electrode can be treated with a material, such as a polymer, followed by applying the zwitterionic polymers onto the treated surface. As a non-limiting example, the surface of the substrate can be modified first with mussel-inspired polydopamine (PDA) films by oxidative self-polymerization of dopamine, and followed by conjugation of the zwitterionic polymers to the PDA film via any reactive group in the reactive side chains of the zwitterionic polymer, such as thiol or amine. It has been previously shown that simple immersion of virtually any substrate in an alkaline aqueous solution of dopamine results in spontaneous deposition of a thin PDA film, with subsequent reactivity of this film toward amines and thiols to form ad-layers (Lee, et al., Science 2007, 318, 426; Lee, et al., Adv. Mater. 2009, 21, 431; and Ham, et al., Angew. Chem. Int. Ed. 2011, 50, 732). Using this method, thiol-containing zwitterionic polymers were attached to the surface of biomaterials to reduce the foreign body responses and fibrosis to these biomaterials.

IV. Methods of Using

The CGMs described herein can be used in applications where improved performance (such as reduced discordance between actual blood glucose levels and signals generated by the CGMs to indicate blood glucose levels), as compared to other commercially available CGMs or control CGMs, are useful or preferred. These include, but are not limited to, monitoring blood glucose levels in subjects that are at risk of developing hyperglycemia, such as diabetic patients. Preferably, the sensor electrode of the CGMs is inserted subcutaneously into a subject at risk of developing hypoglycemia.

The methods, compounds, and compositions herein described are further illustrated in the following examples, which are provided by way of illustration and are not intended to be limiting. It will be appreciated that variations in proportions and alternatives in elements of the components shown will be apparent to those skilled in the art and are within the scope of disclosed forms. All parts or amounts, unless otherwise specified, are by weight.

EXAMPLES General Materials and Methods

(i). Zwitterionic Polymer Synthesis

To synthesize zwitterionic polymers, a two-step chemical reaction process was followed, and after each step the product was dialyzed and lyophilized. For the first reaction, 2-(methacryloyloxy)ethyl 2-(trimethylammonio)ethylphosphate (2.0 g, 6.78 mmol), lipoic acid methacrylate (113 mg, 0.35 mmol), 4-cyano-4-(phenylcarbonothioylthio)pentanoic acid (10 mg, 0.035 mmol) and 4,4′-azobis(4-cyanovaleric acid (2.0 mg, 0.0071 mmol) were weighed and combined in a 10 ml Schlenk flask. Methanol (3.6 mL) and N,N-dimethylacetamide (2.4 mL) were added. The flask was sealed with a rubber septum, the mixture vortexed to get a homogenous solution, then degassed with nitrogen for 10 minutes. The flask was immersed in a preheated oil bath at 70° C. After 5 hr, the reaction was terminated by rapid cooling and exposure to air. The product molecular weight was measured using a Gel Permeation Chromatography (GPC) machine (Malvern Instruments Ltd), and set to be between 8,000 to 10,000 Da. The product was then dialyzed using a 1K Spectra/Pro Dialysis membrane with a 45 mm nominal flat width. After one day of dialysis the solution was lyophilized until dry. The product was then placed in a flask kept at 0° C. while 30 mL of water and methanol was added at a 1:1 ratio. The flask was then degassed and kept under Argon atmosphere and 100 mg of sodium borohydride (NaBH₄) mixed in 2 mL water was slowly added and allowed to react for one hour. At the end of the reaction the pH of the solution was reduced to 3-4 by adding 2N HCl. The product was subsequently dialyzed at 4° C. for three days and then lyophilized for three days to obtain the final product (poly(MPC)-SH), stored in the dark at −20° C.

(ii). X-Ray Photoelectron Spectroscopy (XPS) Analysis

XPS analysis was performed with Physical Electronics Model PHI 5000 Versaprobe II instrument with a monochromatic Al K-alpha X-ray source (1486.6 eV), operating at a base pressure of 3.7e-9 Torr.

(iii). Experimental Animals

Female SKH1 mice (Jackson Laboratory, Bar Harbor, Me., USA), male C57BL/6 BKO mice (Jackson Laboratory, Bar Harbor, Me., USA), and male non-diabetic and diabetic Macaque non-human primates (University of Illinois-Chicago) were used. Mice were housed in a climate-controlled room under 12 h/12 h light/dark cycle with food and water ad libitum. The Animal Care and Use Committees of Massachusetts Institute of Technology (MIT) and University of Illinois-Chicago approved all testing procedures. Deep anesthesia was maintained with 3% isoflurane during sensor insertions for the mice.

(iv). CGM Recording Data Analysis

Medtronic MiniMed Sof-Sensors were used as model sensors for experimentation. The key information recorded by the Sof-Sensor was “Time” and “ISIG signal”. For the recalibration method, all the manually measured BG reads during the entire recording period (3-5 days) were used for calibration. The Medtronic CareLink iPro Therapy Management software autonomously calculated a “Glucose Level” at each time point for the entire recording period. For the non-recalibration analysis, a single BG read on the first day was used for calibration, and the software autonomously calculated “Glucose Level” at each time point based only on the first day measurement. This “Glucose Level” was linearly correlated to the ISIG signal. By fitting the linear relation, the “Glucose Level” for the rest of the days was calculated. In order to compare to actual BG values, the difference was calculated by:

Difference(ti)=[Glucose Level(ti)−BG(ti)]/BG(ti), where Difference(ti), Glucose Level(ti) and BG(ti) were the “Difference”, “Glucose Level” and “BG” at a specific time point (ti). For the statistical analysis of the comparison method differences, the Difference(ti) value of each sensor was averaged.

Example 1: Coating of CGM Sensors with Zwitterionic Polymers Materials and Methods

The poly(MPC)-SH polymer described above, was coupled to the Medtronic MiniMed Sof-Sensor electrode with dopamine-mediated conjugation. Briefly the sensors were immersed in a 3-mg dopamine/mL Tris butter solution (pH 8.5) for 24 hours such that the surface of the electrode was coated with polydopamine films by oxidative self-polymerization of dopamine. The sensors were rinsed with endotoxin free water three times, placed in a 5-mg poly(MPC)-SH/mL Tris Buffer (pH 8.5), degassed with Argon gas for 3 minutes, and covered from light. The sensors in polymer solutions were placed on an orbital shaker at 37° C. for 24 hours, then rinsed with endotoxin free water and stored at room temperature prior to use.

Results

To assess sensor coating and functionality the Medtronic MiniMed CGM was used as a model sensor for experimentation, since it is a typical CGM, commercially available, and the data can be exported for research purposes (Vallejo-Heligon, et al., Acta Biomater. 2016, 30, 106-115; Prichard, et al., J. Diabetes Sci. Technol. 2010, 4, 1055-1062). The Medtronic CGM contains of a recorder and a glucose sensor electrode that detects glucose through an enzymatic approach. The electrode of the sensor is made up of a silicone shell wrapped around an inner metal electrode. The inner electrode contains a conductive gold electrode coated by a thin membrane layer embedded with the glucose specific enzyme, glucose oxidase (GO_(x)) (Prichard, et al., J. Diabetes Sci. Technol. 2010, 4, 1055-1062). This layer selectively immobilizes GO_(x) but also allows small molecules such as glucose, O₂ and H₂O₂ to diffuse through. The GO_(x) catalyzes the oxidation of glucose to gluconolactone, and produces H₂O₂ that changes the electrical current on the electrode surface (Vaddiraju, et al., J. Diabetes Sch. Technol. 2010, 4, 1540-1562; McGarraugh, Diabetes Technol. Ther. 2009, 11, S17-S24; Wang, in Electrochemical Sensors, Biosensors and their Biomedical Applications 57-69 (2008). doi:10.1016/B978-012373738-0.50005-2). The electrical signal—interstitial signal—(ISIG signal) is recorded in the CGM, and can be later exported for analysis by physicians/researchers.

To improve biocompatibility and reduce inflammation, the sensor electrode was coated with a zwitterionic polymer [poly(MPC)] containing methacryloyloxyethyl phosphorylcholine polymer selected from a combinatorial library of zwitterionic polymers, exemplified in FIGS. 1A-1T. Previously, it was shown that zwitterionic surface coating of polystyrene microbeads reduces fibrosis in vivo. (Yesilyurt, et al., Adv. Healthc. Mater. 2017). The zwitterionic poly(MPC) was synthesized with pendant dithiol-containing co-monomers. Poly(MPC) (M_(n): 10 kDa, PDI: 1.1) containing free pendant thiol groups along the backbone [poly(MPC)-SH] was yielded from a reversible addition-fragmentation chain transfer (RAFT) polymerization of methacryloyloxyethyl phosphorylcholine (MPC) and lipoic acid methacrylate monomers, followed by disulfide reduction as shown in Scheme 2. Dopamine-mediated conjugation was applied to couple the poly(MPC)-SH to the sensor electrode. By immersion of the sensor electrode in a 3 mg/mL dopamine solution (pH 8.5) for 24 hours, polydopamine films were coated to the electrode surface by oxidative self-polymerization of dopamine. After rinsing, poly(MPC)-SH was conjugated to the polydopamine coated electrodes by treating the electrode with poly(MPC)-SH solution (pH 8.0) at 37° C. for 24 hours. The coating of the electrode with the zwitterionic polymer was confirmed using X-ray photoelectron spectroscopy (XPS) analysis, FIGS. 2A and 2B. The characteristic peak of phosphorus groups of the poly(MPC) at 188 eV (P2p peak) and at 131 eV (P2s peak) indicates the zwitterionic polymer was successfully coated on the polymer shell of the electrode FIG. 2B. Prior to coating, phosphorus groups were not observed on the electrode FIG. 2A.

Example 2: Glucose Sensing Assay In Vitro Materials and Methods

The in vitro glucose sensing assay was performed with glucose solutions at different concentrations. A 12-well plate was filled with 100 mg/dL glucose solution and covered with parafilm to overcome evaporation and prevent changes in glucose concentration of the solution. Sof-Sensors were inserted through the parafilm and immersed in the glucose solution. After a 20 minute hydration period, the iPro Recorder was attached to the sensor. The glucose solution was spiked every half hour increment with a concentrated amount of glucose, by adding extra glucose solution through a punched hole on the parafilm, to bring the final solution correspondingly higher to 200, 300, and 400 mg/dL. After glucose addition, the solution in the well was slightly mixed with pipetting. The signal from the two non-coated and the two coated sensors was plotted as signal versus time, normalized, and graphed. During the experiment, the parafilm served the purpose of preventing water evaporation.

The schematics of a bioelectrochemical reaction that occurs at the CGM electrode are shown in FIGS. 13A and 13B.

The glucose-specific enzyme glucose oxidase (GO_(x)) was reduced on its flavin group (FAD) upon converting glucose into gluconolactone. The reduced enzyme was converted back to its oxidized form in the present of ambient O₂ with concomitant production of H₂O₂. The Pt anode was applied with a positive potential of around +0.6 V for oxidative detection of the H₂O₂ production, while the cathode detected the O₂ consumption. The amperometric signal from either H₂O₂ production or O₂ correlated with the glucose concentration.

Results

The coated sensors were examined by an in vitro glucose sensing assay, to evaluate whether sensing performance and sensitivity were compromised by the polymer coating or the coating process. In the assay, the initial glucose concentration was 100 mg/dL and it was successively increased to 200, 300, and 400 mg/dL every 30 minutes, allowing the sensors (two non-coated control sensors and two coated sensors) to track the change in glucose concentration. The recorded signal was plotted as signal verses time and normalized, FIG. 3. For both coated and control sensors, as the glucose concentration increased, correspondingly the signal immediately increased, indicating sensitive response to the glucose concentration. The rising edge of the signal is not completely straight, likely due to time required for equilibration of the glucose solution upon spiking in solutions with higher glucose concentrations. The sensing curves of the coated and non-coated sensors overlapped well and the signal responses of the sensors were linearly correlated to the glucose concentration. Overall, these in vitro results indicate that the zwitterionic poly(MPC) coating did not disrupt the performance and response of the sensors.

Example 3: Sensor Functional Testing in Mice and Blood Glucose Testing in Mice Materials and Methods

All MIT committee on animal care (CAC) guidelines for the care and use of laboratory animals were observed. SKH1 mice were anesthetized using 3% Isoflurane. If needed, the area where the glucose sensor was to be implanted was shaved off. The insertion site was cleaned with alcohol wipes. Control and coated Medtronic MiniMed Sof-Sensor glucose sensors were implanted subcutaneously in the mice with a guide needle already on the sensor. Subsequently, the guide needle was removed. Adhesive harness was placed on mice to ensure the sensors stayed in place. After a 15-20 minute sensor hydration period, the iPro2 recording unit was plugged into the sensor base, after which a green blinking light on the unit indicating the device initiated data recording.

After 1-2 hours of sensor insertion in the mice, the first blood glucose (BG) reading was taken. BGs were taken frequently throughout the day (10-13 times a day) for the first three days. Blood glucose levels were measured using the Clarity hand-held monitor and test strips (Clarity Diagnostics, LLC., Boca Raton, Fla.). For each measurement one drop of blood was collected from the tail vein using a lancet (Medipoint, Inc., Mineola, N.Y.). Validation of glucose levels was carried out using a YSI 2900 biochemistry analyzer, per manufacturer instructions (YSI/Xylem Inc., Yellow Springs, Ohio).

Results

In vivo sensing of zwitterionic polymer-coated sensors and control sensors (without coating) was performed in SKH1 mice. The electrode was inserted subcutaneously with a guide needle, and the sensor base and recorder were immobilized on the back of mice with an adhesive tape harness. Following insertion, the mice recovered from anesthesia and were able to move freely. The electrode interacted with interstitial fluid containing glucose, and the electrical signal was recorded at 5 minute intervals for three continuous days. Glucose challenges of 250 mg/mouse were performed to induce glucose level spikes and BG fluctuations on days 1, 2, and 3 of recording. BG values were measured with glucose test strips (8 times each day) on days 1-3 covering the period of glucose challenges. At the end of the 3-day recording period recorders were retrieved from the mice and the stored electrical signals were exported. The results of two representative control sensors and two coated sensors are shown in FIGS. 4A-4D. Additional experiments were performed with more sensors (six control (uncoated) sensors and six experimental (coated) sensors in total.

Medtronic CareLink iPro Therapy Management software was used to convert electrical signals to glucose levels by correlating the electrical signal to a corresponding measured BG value at that same time point. At the time point when BG measurement was performed, the electrical signal was plotted on the x-axis, and the measured BG was plotted on the y-axis. As shown in FIGS. 4A-4D, these data points were plotted as open circles, with different degrees of gray indicating different days. Within a short-time period (<12 hours) the signal versus BG value followed a linear trend. However, for longer periods (>24 hours), this mathematical algorithm to describe the relationship became more complex due to possible changes of the physiologic environment induced by host response including inflammation. The CareLink software fitted the relation between the electrical signal and the BG value for each day using a single linear equation. For the control sensors, the linear relationships of signal calibration versus BG value continued to deviate over all three days indicating sensor performance was disturbed during that timeframe, FIGS. 4A and 4B. In contrast, the coated sensors all showed linear relationships of signal versus BG values that overlapped well across each measurement day, suggesting sensor performance was not disturbed, FIGS. 4C and 4D.

Generated linear regression equations can also be used to fit signal values to BG values, allowing for glucose levels to be calculated based on the recorded electrical signal at the corresponding time point (solid dots in FIGS. 5A-5D). By using all the measured BG values from different days to calibrate the signal (with “recalibration”), the calculated glucose level versus time was plotted as the blue curve (FIGS. 5A-5D). Actual BG values were plotted as black dots for comparison. Gray banded regions in FIGS. 5A-5D were used to visually indicate the time period of day 2. In order to understand manufacturer-mandated requirement of calibrating the control sensor every day, glucose level trends from signal data were generated using only a single, initial measured BG value on the first day, without further calibration (“non-recalibration”) for the next two days. Spiking glucose levels are due to glucose challenges. Based on these results, it was found that the recalibrated glucose levels recorded from control sensors did not overlap well with actual BG values (black dots). Even with frequent recalibration there remained imprecision throughout the first day of recording indicating that calibration of the control sensors cannot completely get rid of inaccuracy and noise. Furthermore, the non-recalibrated glucose trend (red curve) from control sensors deviated more significantly from both the actual BG value and the recalibrated glucose trend, showing that control sensors failed to depict accurate glucose levels without frequent calibration. Conversely, for coated sensors, the recalibrated and non-recalibrated glucose trends (blue vs. red curve) overlapped with each other as well as with measured BG. Thus, coated sensors are able to record glucose levels accurately even without the need to recalibrate every day. These results were observed consistently in additional experiments performed on six other control and six other coated sensors.

For all sensors in FIGS. 5A-5D, the recalibrated and non-recalibrated glucose trends were compared to measured BG values at the appropriate corresponding time points, and their deviation (% difference) from BGs is shown in FIGS. 6A-6D. Control sensor-recorded glucose levels showed a significant difference compared to measured BGs after day 2 when no recalibrations were performed, while the coated sensors showed no significant deviation. For coated and control sensors, comparisons between non-recalibrated versus (re)calibrated glucose trends, non-recalibrated versus measured BGs, and recalibrated versus measured BG values, during the entire recording period, are statistically shown in FIG. 7. (N=6 for each group). Control (uncoated) sensors showed 73±36% inaccuracy of non-recalibrated glucose levels compared to actual BG values; however, recalibration significantly decreased this inaccuracy to 15±17%. Conversely, coated sensors showed only an inaccuracy of 17±11% without recalibration and 11±9% inaccuracy with recalibration. These results suggest that the zwitterionic polymer coating significantly improves the performance and accuracy of CGMs in mice and, equally important, eliminates the (industry norm and manufacturer directed) requirement of re-calibration by painful, repetitive finger-prick BG normalization, often required of users multiple times each day.

Example 4: Investigating Inflammatory Responses Materials and Methods

While the exact mechanisms behind CGM noise and fluctuation still remain unclear, measurement of glucose with commercial sensors is oxygen-based (glucose oxidase) (McGarraugh, Diabetes Technol. Ther. 2009, 11, S17-S24; Wang, in Electrochemical Sensors, Biosensors and their Biomedical Applications 57-69 (2008). doi:10.1016/B978-012373738-0.50005-2), and has been shown to be influenced by the presence of various pharmacological agents or cells that result in significant oxygen or glucose fluctuation (Basu, et al., Diabetes Technol. Ther. 2016, 18 Suppl. 2, S243-7; Klueh, et al., Biomaterials 2014, 35, 3145-3153). In the current investigations, it was hypothesized that the inflammatory response to the materials that the CGM contained, might be the driving force behind signal fluctuation following implantation. To test this hypothesis, the following assays were performed.

(a). IVIS Imaging and Prosense Inflammation

18-24 hours prior to imaging, a dose of 100 uL ProSense 750 Fast Fluorescent Imaging agent (PerkinElmer, Hopkinton, Mass.) was injected intraperitoneally (i.p.) into SKH1 mice with previously inserted Sof-Sensors. In vivo fluorescence imaging was performed using the IVIS Spectrum measurement system (Xenogen, Hopkinton, Mass.). The mice were maintained under 3% isoflurane. All images were subsequently analyzed using the manufacturer's Living Image acquisition and analysis software (Caliper Life Sciences, Hopkinton, Mass.).

(b). Histology

Subcutaneous tissue sections were fixed in 4% paraformaldehyde and sent to the Swanson Biotech Histology Core at the Koch Institute. 5 μm sections processed with both H&E and Masson's trichrome stains were then imaged using an EVOS microscope (Thermo Fisher Scientific, Inc.) at various magnifications, as indicated.

(c). Gene Expression Profile

RNA was extracted from frozen tissues containing control and coated sensors using the Trizol Reagent protocol. The RNA was quantified, diluted, and used with a NanoString machine/kit for gene expression analysis.

Results

(a). IVIS Imaging and Prosense Inflammation

The inflammation profiles after sensor insertion were evaluated with IVIS (In Vivo fluorescence Imaging System) using a Prosense substrate indicating inflammation-associated protease activity (Bratlie, et al., PLoS One, 2010, 5(4), e10032). Each mouse was inserted with either a control or coated electrode and monitored over multiple days post-implantation. The IVIS inflammation profiles were quantified and shown in FIG. 8. Correlating with the timeline of observed CGM sensor noise, host inflammation responses are largely acute and most prominent within the first 1-3 days following insertion into the subcutaneous space. The inflammation profiles decreased with time from day 1 to day 8, and, on average, at all time points measured (days 1, 3, and 8 post-insertion), skin around zwitterionic coated sensors had reduced inflammation profiles compared to the control sensors. The similar kinetics of this dissipating response to those of decreasing signal noise over time following CGM implantation suggest that an early host inflammation response is interfering with sensor function and the ability for CGMs to accurately and reliably measure glucose levels. Furthermore, the observed inflammation is also foreign body-induced and independent of wound injury, as insertion and immediate removal of the delivery-assisting guide needle does not result in significant inflammation. Therefore, the observed interfering host inflammatory response requires a material implant to be present. In addition, four electrodes including two control electrodes, one control polyurethane tubing, and one coated electrode were also inserted into the same mice to compare their inflammation profiles directly. Similar to the results observed earlier, the inflammation profiles on the skin around each inserted material decreased with time from day 1 to day 8. The inflammation on the skin around the coated electrode was also significantly reduced in comparison to the other three control samples.

(b). Histology

To better understand this inflammation, sensor-embedded tissues were dissected and prepared for histological examination. Cellular infiltration (H&E) and fibrotic tissue overgrowth (Masson's Tri-chrome) surrounding the implanted non-coated electrode (control) increased with time from day 1 to day 8, while there is little tissue overgrowth observed on tissue surrounding the coated sensor, indicating the zwitterionic coating also resulted in significant fibrotic reduction in SKH1 mice. While fibrosis increases over time, sensor noise is limited to early immune inflammation throughout the first 3 days following insertion (FIGS. 4A-4D, 5A-5D, 6A-6D, and 7). As CGM noise also continuously decreases over this time in an inversely proportional relationship, it is not believed that fibrosis is responsible.

(c). Gene Expression Profile

Multiplexed NanoString gene expression analysis was performed to compare tissues from control and coated implants to mock saline injected background (FIGS. 9A-9F). The results indicate many inflammatory markers, cyto/chemokines Cxcl15, Tnfsf18, Cxcl17, IL17b, and Ccl20, as well as B cell marker Cd19, were increased in tissues with control electrodes, especially 1 day following implantation (FIGS. 9A-9F). Importantly, these factors were not increased, and in some cases were suppressed below Mock background levels in tissues surrounding zwitterionic coated CGMs. In addition, coated sensors also had suppressed (lower than Mock background) levels of macrophage markers Cd68 and Emr1 (F4/80), eosinophil marker Prg2, immune marker Kit, as well as numerous other cytokines and cytokine receptors. Corroborating the earlier Masson's trichrome histology, tissue surrounding coated sensors also had lower levels of fibrosis-associated genes such as myofibroblast marker alpha Smooth muscle actin (αSMactin) and collagen 1a1 (Col1a1). These results suggest that the zwitterionic coating eliminates numerous inflammatory responses that may play a role in or be responsible for sensor-associated noise, as well as corroborates the histological determination that coated sensors have reduced fibrosis.

(viii). Sensor Functional Testing in NHPs

The non-human primates were anesthetized and 4 coated and 4 non-coated Medtronic MiniMed Sof-Sensor glucose sensors were inserted subcutaneously on the back. Recorders were attached and a breathable jacket was placed over the sensors so the animals would not grab/pull off the sensors due to their social grooming behaviors. Four glucose readings were taken on day 1 and standard IVGTT (50% dextrose solution) was performed. On day 6, the recorders were taken off the sensors and the data was uploaded to the online Medtronic CareLink iPro Therapy Management software portal.

Example 5: Sensor Functional Testing in Non-Human Primates (NHPs) Materials and Methods

Zwitterionic polymer-coated sensors were also tested in non-human primates (NHPs). For each testing run, four coated and four control sensors were subcutaneously inserted into the back of non-diabetic or diabetic NHPs. The recorders were also sutured into the skin, and a zipped jacket was placed over the sensors to prevent them from falling out or being pulled out by the NHPs which have social grooming behavior. Glucose levels were then recorded for 5 continuous days. Non-diabetic and diabetic NHPs were glucose-challenged with 0.5 g glucose/kg NHP body weight by IV infusion (IVGTT) on each of the first three or four days, respectively, to induce dynamic signal spikes and fluctuations in their glucose levels. This was done to test control (non-coated) and zwitterionic polymer-coated sensors not just over an extended period of time but also across BG extremes, for accuracy assessment over a larger dynamic range of glucose measurements.

Results

In non-diabetic NHPs, resting or steady state glucose levels were stable except during glucose challenges, whereas in the diabetic NHPs, as expected, glucose levels in between IVGTTs showed wide fluctuations. The glucose levels of diabetic NHPs fluctuated significantly throughout the day, allowing us to appropriately evaluate the performance of the coated sensors, in comparison to controls, in accurately monitoring glucose levels as needed for diabetic patients. After recording the recorders were retrieved from both diabetic and non-diabetic NHPs, and the recorded data was exported.

As done previously in the SKH1 model, the electrical signal exported to the iPro2 Medtronic CareLink software was plotted as time on the x-axis, and with measured BG values on the y-axis (FIGS. 10A-10D). Linear regression of signal versus BG values showed decreased slopes over time, highest on day 1 and significantly reduced into days 2 and 3 of continual sensing. This trend, similar to what was seen for the SKH1 mouse model, was also observed for control sensors in both diabetic and non-diabetic NHPs, indicating sensor performance was disturbed to a greater extent by an early period response consistent with when significant host inflammation to foreign objects was observed (i.e., CGM insertion and presence). In contrast, coated sensors showed near-identical (not statistically different) slopes of signal versus BG values over days 1, 2, and 3 of continuous measurement, indicating sensor performance was left undisturbed.

Once more, as performed during mouse model testing, electrical signals were converted to glucose levels by using either a single BG value on the first day without additional recalibration throughout the rest of the monitoring period (FIGS. 11A-11D) or with constant recalibration with all measured BG values taken throughout the testing period. Individually-measured BG values were again plotted for comparison (FIGS. 11A-11D). The results of representative control and coated sensors are shown in FIGS. 11A-11D. Similar experiments performed with additional sensors (three control (uncoated) and three experimental (coated)) showed similar trends. Furthermore, recalibrated vs. non-recalibrated glucose level trend differences were quantified throughout the entire recording period. Glucose level trend recording by the control sensors on both non-diabetic and diabetic NHPs showed a significant difference as compared to actual, measured BGs. Conversely, as was the case with testing in mice, coated sensors showed no significant difference as compared to recorded glucose levels. In the non-diabetic model, the control sensors showed a 48±26% inaccuracy of the non-recalibrated glucose level compared to measured BGs, while recalibration significantly decreased this inaccuracy to 21±17%, FIG. 12A. The non-recalibrated vs. recalibrated trends were also significantly different from each other. For the coated sensors, they only showed an inaccuracy of 18±17% for non-recalibration and 16±13% inaccuracy for recalibration every day. These findings were also observed in diabetic NHPs, where control sensors showed 32±30% inaccuracy non-recalibrated, or 23±14% with recalibration, FIG. 12B. Coated sensors only showed an inaccuracy of 22±14% for non-recalibration and 24±14% inaccuracy for recalibration every day. This data indicates the zwitterionic coating still has a functional and significant effect on the functional readout of CGMs and in reducing overall noise in higher order non-human primates, regardless of diabetic state. Lastly, both coated and non-coated sensors were implanted in both non-diabetic and diabetic monkeys, and the tissue with embedded sensors was dissected and stained for histological examination. Similar to the results in SKH1 mice, tissue overgrowth increased with time from day 1 to day 8, and the zwitterionic coating significantly reduced fibrosis in both non-diabetic and diabetic implanted NHP models.

These results show that the zwitterionic polymer coating significantly improves the performance and accuracy of CGMs in the higher order non-human primate model. Furthermore, and of equal significance, the coating allows for just a single stand-alone BG calibration taken immediately after insertion, for the entire recording period. In doing so, this coating-based technology eliminates the requirement for constant BG calibration multiple times (4-6 times by manufacturer guidelines) throughout the first day of use and at least twice every day thereafter, a tedious and stressful process for patients to do with finger-prick tests (Newman and Turner, Biosensors and Bioelectronics 2005, 20, 2435-2453). The result of the zwitterionic polymer coating improving sensor accuracy is repeatable and holds true across two animal models (SKH1 mice and NHPs) as well as in both healthy and diabetic animals.

Foreign body response including inflammatory events and fibrosis due to wound-healing processes are a major hindrance to implanted biomaterial sensors (Onuki, et al., J. Diabetes Sci. Technol. 2008, 2, 1003-1015; Anderson, Annu. Rev. Mater. Res. 2001, 31, 81-110; Moussy, Sensors 2002, 2002 IEEE). To combat such responses, which can interfere with sensing and lead to device failure, surface modifications (Meyers and Grinstaff, Chem. Rev. 2012, 112, 1615-1632) or drug delivery systems (Vallejo-Heligon, et al., Acta Biomater. 2016, 30, 106-115; Klueh, et al., J. Diabetes Sci. Technol. 2007, 1, 496-504) have been developed to enhance their biocompatibility. However, limited success has been achieved on alleviating host response to CGMs in order to fully restore their functional reliability. Among the many natural and synthetic materials used as coatings for implantable devices, zwitterionic polymers have received considerable attention due to their ultra-low fouling properties and hindering of non-specific protein adsorption, leading to reduced capsular formation (Vaisocherová, et al., Anal. Chem. 2008, 80, 7894-7901; Zhang, et al., Nat. Biotechnol. 2013, 31, 553-556; Zhao, et al., J. Memb. Sci. 2011, 369, 5-12).

Here it was shown that while inflammation is a primary cause of sensor noise, the variation seen early following implantation is not due to fibrose capsule formation. Instead, the data show that a zwitterionic polymer coating, applied to CGMs (e.g. Medtronic CGMs), can overcome acute, interfering host inflammation and sensor noise, thereby removing the associated requirement for constant BG calibration. Dopamine-mediated conjugation was developed to couple the zwitterionic polymer to sensors. In vitro glucose measurements confirmed that the sensor maintained sensing performance and response after coating. The coated and non-coated control CGMs were tested in two animal models, SKH1 mice and non-human primates (NHPs). Uncoated sensors show significant noise within the first day after implantation and required BG calibration every day to correct signal trends. In contrast, the zwitterionic polymer-coated sensors showed significant improvement on eliminating sensing noise and were able to record glucose levels accurately without recalibrating beyond the first glucose blood measurement, necessary to convert raw sensor signals to real-time BG values (Bequette, J. Diabetes Sci. Technol. 2010, 4, 404-18). This is in contrast to uncoated control CGMs, which required recalibration at least 4 times on the first day of use and at least 2 times every day thereafter (iPro2 User Guide (Medtronic MiniMed, 2010)). These results were observed in both SKH1 mice and NHPs models as well as in both diabetic and healthy non-diabetic animals. Inflammation profiles following sensor implantation were measured using a number of orthogonal methods including In Vivo Imaging using pro-sense fluorescent imaging, histological studies, and gene profiling. The zwitterionic polymer coating is shown to reduce inflammation and CGM noise as compared to naive sensors. This technology is significant for subcutaneously embedded glucose monitors as it overcomes the most significant issue of sensor noise, deviation from actual measured BGs, while also improving user experience by eliminating the need for recalibration, traditionally often occurring multiple times throughout the first week of sensor use.

In summary, the data show that coating the sensor electrode of a CGM with a zwitterionic polymer eliminated sensor noise and the requirement of frequent BG re-calibration. Coated and naive sensors were tested across two animal models, SKH1 mice and non-diabetic and diabetic NHPs. Across all animal models tested, the coated sensors were able to record BG levels accurately without recalibration and showed significant improvement in reducing sensing noise, whereas non-coated sensors began to show significant noise even at the beginning of the first day following implantation. Inflammation profile studies indicate the zwitterionic coating significantly reduced inflammation during the early stages after sensor implantation. Gene expression profiling also established that the zwitterionic coating completely inhibited or suppressed (below background) levels of numerous cytokines and immune markers that may be associated with noise for control CGMs. The current work has successfully improved the function via also improving the biocompatibility of implantable glucose monitors, and, in turn, helped CGMs gain independence from requiring concomitant BG finger-prick testing, a major hurdle toward FDA approval as a stand-alone monitoring device for diabetic patients.

Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of skill in the art to which the disclosed invention belongs. Publications cited herein and the materials for which they are cited are specifically incorporated by reference.

Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the following claims to be encompassed by the following claims. 

1. A continuous glucose monitor (CGM) comprising a sensor electrode partially or completely coated with one or more layers of a material comprising a zwitterionic polymer.
 2. The CGM of claim 1, wherein the CGM exhibits reduced discordance between an actual physical measurement and a signal generated by the CGM to indicate levels of the actual physical measurement as compared the same CGM with an uncoated sensor electrode, when at least the sensor electrode of the CGM is in contact with a tissue fluid.
 3. The CGM of claim 2, wherein the CGM is calibrated once post-implantation to match the signal generated to the actual physical measurement.
 4. The CGM of claim 2, wherein the actual physical measurement is blood glucose level.
 5. The CGM of claim 4, wherein the blood glucose level is measured using a direct blood glucose measurement.
 6. The CGM of claim 1, wherein the zwitterionic polymer is non-covalently attached, covalently attached, or both, to a surface of the sensor electrode.
 7. The CGM of claim 1, wherein a second material is coated on the surface of the sensor electrode prior to coating with the zwitterionic polymer.
 8. The CMG of claim 6, wherein the second material is polydopamine.
 9. The CGM of claim 1, wherein the zwitterionic polymer comprises monomer subunit A, and optionally monomer subunits B, C, or both, wherein: each A is a zwitterionic monomer; each B is a monomer having a reactive side chain; and each C is independently a hydrophobic monomer, or a neutral hydrophilic monomer, wherein the reactive side chain is d-R₁—Y; wherein d is the point of covalent attachment of the reactive side chain to the backbone of the polymer; wherein: R₁ is alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, alkoxy, substituted alkoxy, aroxy, substituted aroxy, alkylthio, substituted alkylthio, arylthio, substituted arylthio, carbonyl, substituted carbonyl, carboxyl, substituted carboxyl, amino, substituted amino, amido, substituted amido, sulfonyl, substituted sulfonyl, sulfamoyl, substituted sulfamoyl, phosphonyl, substituted phosphonyl, polyaryl, substituted polyaryl, C₃-C₂₀ cyclic, substituted C₃-C₂₀ cyclic, heterocyclic, substituted heterocyclic, amino acid, poly(ethylene glycol), poly(lactic-co-glycolic acid), peptide, or polypeptide group; Y is propane-1,3-dithiol, 1,2-dithiolan-3-yl, 1,2-dithiol-3-ylidene, amine, hydrogen, —SH, maleimide, aziridine, —N₃, —CN, acryloyl, acrylamide, —C(O)OR₂, —C(O)R₃, vinyl sulfone, —OH, cyanate, thiocyanate, isocyanate, isothiocyanate, alkoxysilane, vinyl silane, silicon hydride, —NR₄R₅, acetohydrazide, acyl azide, acyl halides, N-hydroxysuccinimide ester, sulfonyl chloride, glyoxal, epoxide, carbodiimides, aryl halides, imido ester; wherein R₂, R₄, and R₅, are, independently, hydrogen, amino, hydroxyl, thiol, oxo, phosphate, or substituted or unsubstituted C₁-C₁₀ alkyl, C₁-C₁₀ alkylene, C₂-C₁₀ alkenyl, C₂-C₁₀ alkynyl, C₁-C₁₀ alkoxy, C₁-C₁₀ alkylamino, C₁-C₁₀ alkylthio, aryl, substituted aryl, heteroaryl, substituted heteroaryl, alkoxy, substituted alkoxy, aroxy, substituted aroxy, alkylthio, substituted alkylthio, arylthio, substituted arylthio, carbonyl, substituted carbonyl, carboxyl, substituted carboxyl, amino, substituted amino, amido, substituted amido, polyaryl, substituted polyaryl, C₃-C₂₀ cyclic, substituted C₃-C₂₀ cyclic, heterocyclic, or substituted heterocyclic; and wherein R₃ is hydrogen, amino, hydroxyl, thiol, oxo, phosphate, or substituted or unsubstituted C₁-C₁₀ alkyl, C₁-C₁₀ alkylene, C₂-C₁₀ alkenyl, C₂-C₁₀ alkynyl, C₁-C₁₀ alkoxy, C₁-C₁₀ alkylamino, C₁-C₁₀ alkylthio, aryl, substituted aryl, heteroaryl, substituted heteroaryl, alkoxy, substituted alkoxy, aroxy, substituted aroxy, alkylthio, substituted alkylthio, arylthio, substituted arylthio, carbonyl, substituted carbonyl, carboxyl, substituted carboxyl, amino, substituted amino, amido, substituted amido, polyaryl, substituted polyaryl, C₃-C₂₀ cyclic, substituted C₃-C₂₀ cyclic, heterocyclic, or +substituted heterocyclic.
 10. The CGM of claim 9, wherein R₁ is -Aq-unsubstituted C₁-C₁₀ alkylene-Bq-unsubstituted C₁-C₁₀ alkylene-, Aq-unsubstituted C₁-C₁₀ alkylene-Bq-substituted C₁-C₁₀ alkylene-, -Aq-substituted C₁-C₁₀ alkylene-Bq-unsubstituted C₁-C₁₀ alkylene-, or Aq-substituted C₁-C₁₀ alkylene-Bq-substituted C₁-C₁₀ alkylene-, wherein Aq and Bq are independently —C(O)O—, —C(O)NH—, —OC(O)—, —NHC(O)—, —O—, —NH—NHC(O)—, —OC(O)NH—, —NHC(O)O—, —C(O)—, —OC(O)O—, —S(═O₂)₂—, —S(═O)—, —S—, —N═N—, or —N═CH—.
 11. The CGM of claim 9, wherein R₁ is —C(O)O-unsubstituted C₂ alkylene-NHC(O)-unsubstituted C₄ alkylene-, —C(O)O-unsubstituted C₂ alkylene-NHC(O)-substituted C₄ alkylene-, —C(O)O-substituted C₂ alkylene-NHC(O)-unsubstituted C₄ alkylene-, or —C(O)O-substituted C₂ alkylene-NHC(O)-substituted C₄ alkylene-.
 12. The CGM of claim 9, wherein Y is Y is propane-1,3-dithiol, 1,2-dithiolan-3-yl, 1,2-dithiol-3-ylidene, amine, hydrogen, or —SH.
 13. The CGM of claim 9, wherein the reactive side chain comprises a structure selected from the group consisting of


14. The CGM of claim 9, wherein the zwitterionic monomer subunit comprises a betaine, selected from the group consisting of carboxybetaine moiety, a sulfobetaine moiety, or a phosphoryl choline moiety.
 15. The CGM of claim 9, wherein the zwitterionic moiety has a formula:

wherein d is the point of covalent attachment of the zwitterionic moiety to the backbone of the polymer; Z is a carboxylate, phosphate, phosphonic, phosphonate, sulfate, sulfinic, or sulfonate; and R₆-R₁₈ are independently unsubstituted alkyl, substituted alkyl, unsubstituted alkenyl, substituted alkylene, unsubstituted alkylene, substituted alkenyl, unsubstituted alkynyl, substituted alkynyl, unsubstituted aryl, substituted aryl, unsubstituted heteroaryl, substituted heteroaryl, unsubstituted alkoxy, substituted alkoxy, unsubstituted aroxy, substituted aroxy, unsubstituted alkylthio, substituted alkylthio, unsubstituted arylthio, substituted arylthio, unsubstituted carbonyl, substituted carbonyl, unsubstituted carboxyl, substituted carboxyl, unsubstituted amino, substituted amino, unsubstituted amido, substituted amido, unsubstituted sulfonyl, substituted sulfonyl, unsubstituted sulfamoyl, substituted sulfamoyl, unsubstituted phosphonyl, substituted phosphonyl, unsubstituted polyaryl, substituted polyaryl, unsubstituted C₃-C₂₀ cyclic, substituted C₃-C₂₀ cyclic, unsubstituted C₃-C₂₀ heterocyclic, substituted C₃-C₂₀ heterocyclic, amino acid, poly(ethylene glycol), poly(lactic-co-glycolic acid), peptide, or polypeptide group.
 16. The CGM of claim 15, wherein R₆-R₁₈ are independently unsubstituted C₁-C₁₀ alkyl, substituted C₁-C₁₀ alkyl, unsubstituted C₁-C₁₀ alkenyl, substituted C₁-C₁₀ alkylene, unsubstituted C₁-C₁₀ alkylene, substituted C₁-C₁₀ alkenyl, unsubstituted C₁-C₁₀ alkynyl, substituted C₁-C₁₀ alkynyl, unsubstituted aryl, substituted aryl, unsubstituted heteroaryl, substituted heteroaryl, unsubstituted C₁-C₁₀ alkoxy, substituted C₁-C₁₀ alkoxy, unsubstituted aroxy, substituted aroxy, unsubstituted C₁-C₁₀ alkylthio, substituted C₁-C₁₀ alkylthio, unsubstituted arylthio, substituted arylthio, unsubstituted C₁-C₁₀ carbonyl, substituted C₁-C₁₀ carbonyl, unsubstituted C₁-C₁₀ carboxyl, substituted C₁-C₁₀ carboxyl, unsubstituted C₁-C₁₀ amino, substituted C₁-C₁₀ amino, unsubstituted C₁-C₁₀ amido, substituted C₁-C₁₀ amido, unsubstituted C₁-C₁₀ sulfonyl, substituted C₁-C₁₀ sulfonyl, unsubstituted C₁-C₁₀ sulfamoyl, substituted C₁-C₁₀ sulfamoyl, unsubstituted C₁-C₁₀ phosphonyl, substituted C₁-C₁₀ phosphonyl, unsubstituted polyaryl, substituted polyaryl, unsubstituted C₃-C₂₀ cyclic, substituted C₃-C₂₀ cyclic, unsubstituted C₃-C₂₀ heterocyclic, or substituted C₃-C₂₀ heterocyclic.
 17. The CGM of claim 15, wherein R₆, R₉, R₁₀, R₁₁ and R₁₅, are independently unsubstituted C₁-C₅ alkyl, substituted C₁-C₅ alkyl, substituted C₁-C₅ alkylene, or unsubstituted C₁-C₅ alkylene, C₁-C₅ alkoxy, substituted C₁-C₅ alkoxy, unsubstituted aroxy, substituted aroxy, unsubstituted C₁-C₅ alkylthio, substituted C₁-C₅ alkylthio, unsubstituted arylthio, substituted arylthio, unsubstituted C₁-C₅ carbonyl, substituted C₁-C₅ carbonyl, unsubstituted C₁-C₅ carboxyl, substituted C₁-C₅ carboxyl, unsubstituted C₁-C₅ amino, substituted C₁-C₅ amino, unsubstituted C₁-C₅ amido, substituted C₁-C₅ amido, unsubstituted C₁-C₅ sulfonyl, substituted C₁-C₅ sulfonyl, unsubstituted C₁-C₅ sulfamoyl, substituted C₁-C₅ sulfamoyl, unsubstituted C₁-C₅ phosphonyl, or substituted C₁-C₅ phosphonyl.
 18. The CGM of claim 15, wherein R₇, R₈, R₁₂, R₁₃, R₁₄, R₁₆, R₁₇, and R₁₈, are independently hydrogen, unsubstituted C₁-C₅ alkyl, or substituted C₁-C₅ alkyl.
 19. The CGM of claim 9, wherein the zwitterionic monomer comprises a moiety selected from the group consisting of


20. The CGM of claim 9, wherein at least one A is a first zwitterionic monomer and at least one B is a monomer with a reactive side chain.
 21. The CGM of claim 9, wherein at least one C is a hydrophobic monomer comprising a hydrophobic side chain having the formula:

wherein d is the point of covalent attachment of the hydrophobic side chain to the backbone of the polymer; and R₁₉ and R₂₀ independently unsubstituted alkyl, substituted alkyl, unsubstituted alkenyl, substituted alkenyl, unsubstituted alkynyl, substituted alkynyl, unsubstituted aryl, substituted aryl, unsubstituted heteroaryl, substituted heteroaryl, unsubstituted alkoxy, substituted alkoxy, unsubstituted aroxy, substituted aroxy, unsubstituted alkylthio, substituted alkylthio, unsubstituted arylthio, substituted arylthio, unsubstituted carbonyl, substituted carbonyl, unsubstituted carboxyl, substituted carboxyl, unsubstituted amino, substituted amino, unsubstituted amido, substituted amido, unsubstituted sulfonyl, substituted sulfonyl, unsubstituted sulfamoyl, substituted sulfamoyl, unsubstituted phosphonyl, substituted phosphonyl, —O—, —S—, —NH—NHC(O)—, —N═N—, —N═CH—, unsubstituted polyaryl, substituted polyaryl, unsubstituted C₃-C₂₀ cyclic, substituted C₃-C₂₀ cyclic, unsubstituted C₃-C₂₀ heterocyclic, substituted C₃-C₂₀ heterocyclic, amino acid, poly(ethylene glycol), poly(lactic-co-glycolic acid), peptide, or polypeptide group.
 22. The CGM of 21, wherein R₁₉ is —C(O)NH—, —C(O)O—, —NHC(O)—, —OC(O)—, —O—, —NH—NHC(O)—, —OC(O)NH—, —NHC(O)O—, —C(O)—, —OC(O)O—, —S(═O₂)₂—, —S(═O)—, —S—, —N═N—, or —N═CH—.
 23. The CGM of claim 21, wherein R₂₀ has the structure: -Az-Bz-(-Cz)δ,   Formula VII wherein δ is an integer between 0 and 10, inclusive, preferably δ is 1; Az is

wherein R₃₁ in Az is —(CR₃₂R₃₂)_(p)—; p is an integer from 0 to 5; each R₃₂ is hydrogen, unsubstituted alkyl, or substituted alkyl; each R^(e) is independently unsubstituted alkyl, substituted alkyl, unsubstituted alkenyl, unsubstituted alkenyl, unsubstituted alkynyl, substituted alkynyl, unsubstituted alkoxy, substituted alkoxy, unsubstituted alkylamino, substituted alkylamino, unsubstituted dialkylamino, substituted dialkylamino, hydroxy, unsubstituted aryl, substituted aryl, unsubstituted heteroaryl, substituted heteroaryl, unsubstituted carboxyl, substituted carboxyl, unsubstituted amino, substituted amino, unsubstituted amido, substituted amido, unsubstituted C₃-C₂₀ cyclic, substituted C₃-C₂₀ cyclic, unsubstituted C₃-C₂₀ heterocyclic, or substituted C₃-C₂₀ heterocyclic; y is an integer between 0 and 11, inclusive; R₂₅, R₂₆, R₂₇, R₂₈, R₂₉, and R₃₀ are independently C or N, wherein the bonds between adjacent R₂₅ to R₃₀ are double or single according to valency, and wherein R₂₅ to R₃₀ are bound to none, one, or two hydrogens according to valency, or Az is

wherein R₃₂, R₃₃, R₃₄, R₃₅, R₃₆, R₃₇, R₃₈, and R₃₉ in Az are independently hydrogen, unsubstituted alkyl, substituted alkyl, unsubstituted alkenyl, substituted alkenyl, unsubstituted alkynyl, substituted alkynyl, unsubstituted phenyl, substituted phenyl, unsubstituted aryl, substituted aryl, unsubstituted heteroaryl, substituted heteroaryl, unsubstituted arylalkyl, substituted arylalkyl, unsubstituted alkoxy, substituted alkoxy, unsubstituted aroxy, substituted aroxy, unsubstituted carbonyl, substituted carbonyl, unsubstituted carboxyl, substituted carboxyl, unsubstituted amino, substituted amino, unsubstituted amido, substituted amido, unsubstituted C₃-C₂₀ cyclic, substituted C₃-C₂₀ cyclic, unsubstituted C₃-C₂₀ heterocyclic, substituted C₃-C₂₀ heterocyclic, poly(ethylene glycol), or poly(lactic-co-glycolic acid); k is an integer from 0 to 20; each X_(d) is independently absent, 0, or S; and R^(c) is Bz; wherein Bz is

wherein R₄₅ in Bz is —(CR₄₆R₄₆)_(p)—; p is an integer from 0 to 5; each R₄₆ is hydrogen, unsubstituted alkyl, or substituted alkyl; each R^(d) is independently unsubstituted alkyl, substituted alkyl, unsubstituted alkenyl, unsubstituted alkenyl, unsubstituted alkynyl, substituted alkynyl, unsubstituted alkoxy, substituted alkoxy, unsubstituted alkylamino, substituted alkylamino, unsubstituted dialkylamino, substituted dialkylamino, hydroxy, unsubstituted aryl, substituted aryl, unsubstituted heteroaryl, substituted heteroaryl, unsubstituted carboxyl, substituted carboxyl, unsubstituted amino, substituted amino, unsubstituted amido, substituted amido, unsubstituted C₃-C₂₀ cyclic, substituted C₃-C₂₀ cyclic, unsubstituted C₃-C₂₀ heterocyclic, or substituted C₃-C₂₀ heterocyclic; w is an integer between 0 and 4, inclusive; each R₄₀, R₄₁, R₄₂, R₄₃, and R₄₄, are independently C or N, wherein the bonds between adjacent R₄₀ to R₄₄ are double or single according to valency, and wherein R₄₀ to R₄₄ are bound to none, one, or two hydrogens according to valency; and wherein Cz is

wherein R₃₁ in Cz is —(CR₃₂R₃₂)_(p)— or —(CR₃₂R₃₂)_(p)—X_(b)—(CR₃₂R₃₂)_(q)—; p and q are independently integers between 0 to 5, inclusive; each R₃₂ is hydrogen, unsubstituted alkyl, or substituted alkyl; X_(b) is absent, —O—, —S—, —S(O)—, —S(O)₂—, or NR₄₇; R₄₇ is unsubstituted alkyl or substituted alkyl; each R^(e) is independently unsubstituted alkyl, substituted alkyl, unsubstituted alkenyl, unsubstituted alkenyl, unsubstituted alkynyl, substituted alkynyl, unsubstituted alkoxy, substituted alkoxy, unsubstituted alkylamino, substituted alkylamino, unsubstituted dialkylamino, substituted dialkylamino, hydroxy, unsubstituted aryl, substituted aryl, unsubstituted heteroaryl, substituted heteroaryl, unsubstituted carboxyl, substituted carboxyl, unsubstituted amino, substituted amino, unsubstituted amido, substituted amido, unsubstituted C₃-C₂₀ cyclic, substituted C₃-C₂₀ cyclic, unsubstituted C₃-C₂₀ heterocyclic, or substituted C₃-C₂₀ heterocyclic; y is an integer between 0 and 11, inclusive; R₂₅, R₂₆, R₂₇, R₂₈, R₂₉, and R₃₀ are independently C or N, wherein the bonds between adjacent R₂₅ to R₃₀ are double or single according to valency, and wherein R₂₅ to R₃₀ are bound to none, one, or two hydrogens according to valency.
 24. The zwitterionic polymer of claim 9, wherein the neutral hydrophilic monomer comprises a hydrophilic side chain having the formula:

wherein, d is the point of covalent attachment of the neutral hydrophilic side chain to the backbone of the polymer; p is an integer between 1 and 10,000, inclusive, preferably between 1 and 30, inclusive, R₂₁ is unsubstituted alkyl, substituted alkyl, unsubstituted alkenyl, substituted alkenyl, unsubstituted alkynyl, substituted alkynyl, unsubstituted aryl, substituted aryl, unsubstituted heteroaryl, substituted heteroaryl, unsubstituted alkoxy, substituted alkoxy, unsubstituted aroxy, substituted aroxy, unsubstituted alkylthio, substituted alkylthio, unsubstituted arylthio, substituted arylthio, unsubstituted carbonyl, substituted carbonyl, unsubstituted carboxyl, substituted carboxyl, unsubstituted amino, substituted amino, unsubstituted amido, substituted amido, unsubstituted sulfonyl, substituted sulfonyl, unsubstituted sulfamoyl, substituted sulfamoyl, unsubstituted phosphonyl, substituted phosphonyl, unsubstituted polyaryl, substituted polyaryl, unsubstituted C₃-C₂₀ cyclic, substituted C₃-C₂₀ cyclic, unsubstituted C₃-C₂₀ heterocyclic, substituted C₃-C₂₀ heterocyclic, amino acid, poly(ethylene glycol), poly(lactic-co-glycolic acid), peptide, or polypeptide group; and R₂₂, R₂₃, and R₂₄ are independently hydrogen, alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, alkoxy, aroxy, substituted aroxy, alkylthio, substituted alkylthio, arylthio, substituted arylthio, carbonyl, carboxyl, amido, sulfonyl, substituted sulfonyl, sulfamoyl, substituted sulfamoyl, phosphonyl, substituted phosphonyl, polyaryl, substituted polyaryl, C₃-C₂₀ cyclic, substituted C₃-C₂₀ cyclic, heterocyclic, substituted heterocyclic, amino acid, poly(lactic-co-glycolic acid), peptide, or polypeptide group.
 25. The CGM of claim 1, wherein the zwitterionic polymer comprises:

wherein, x and y are independently integers between 1 and 1000, inclusive, preferably x is between 10 and 200, inclusive, preferably y is between 2 and 20, inclusive; and z is between 0 and 1000, inclusive, preferably z is between 10 and 200, inclusive.
 26. A method of reducing discordance between an actual physical measurement and a signal generated by a CGM to indicate levels of the measurement, the method comprising: implanting at least the sensor electrode of the CGM of claim 1 at a location where the signal will be generated; and optionally calibrating the CGM initially to match the signal generated by the CGM to the actual physical measurement.
 27. The method of claim 26, wherein the actual physical measurement is blood glucose level.
 28. The method of claim 27, wherein the blood glucose level is measured using a direct blood glucose measurement. 